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• Webcast Q&A: Los Angeles Department of Building & Safety Lowers Customer Service Costs with Oracle WebCenter

  - by Kellsey Ruppel

  This week we had the fifth webcast in our WebCenter in Action webcast series, "Los Angeles Department of Building & Safety Lowers Customer Service Costs with Oracle WebCenter", where customers Giovani Dacumos and Minh Ong from the Los Angeles Department of Building & Safety (LADBS), and Sheetal Paranjpye and Rajiv Desai from Oracle Partner 3Di, shared how Oracle WebCenter is powering LADBS' externally facing website and providing a superior self-service experience for their customers. We asked the speakers to provide some dialogue for Q&A.   Giovani Dacumos, Director of Systems and Minh Ong, LADBS Q: Did you run into any issues when integrating all of the different applications together?A: Yes. We did have issues integrating a secure sign on between the portal and other legacy applications. We used portlets and iframes to overcome those.  This is a new technology for us and we are also learning as we go so there were a lot of challenges in developing and implementing our vision. Q: What has been the biggest benefit your end users have seen?A: The biggest benefit for our ends users is ease-of-use. We've given them a system that provided a new and improved source of information, as well as a very organized flow of transaction processing. It has made our online service very user friendly. Q: Was there any resistance internally when implementing the solution? If so, how did you overcome that?A: There was no internal resistance during the implementation, only challenges. As mentioned earlier, this is a new technology for us. We've come across issues that needed assistance from Oracle. Working with 3Di and Oracle has helped us tremendously to find solutions to our implementation issues. Q: Given the performance, what do you estimate to be the top end capacity of the system? A: With the current performance and architecture we have, we are able to support approx 300-400 concurrent users.  We would need more hardware to support additional user load. Q: What's the overview or summary of feedback from the users interacting with the site?A: LADBS has a wide spectrum of customers, from simple users like homeowners to large construction firms. Anything new that we offer could be a little bit challenging for some, but overall, the customers liked it. They saw a huge improvement on the usability. Q: Can you describe the impressions about the site before and after the project within LADBS?A: The old site was using old technology and it was hard for us to keep on building into it as we got more business requirements. It made our application seem a bit complicated.  It was confusing for our new customers to use and we've improved on this with the new site. It's now easier for them to complete their transactions and, at the same time, allowed us to provide more useful information. Sheetal Paranjpye and Rajiv Desai, 3Di Q: Did you run into any obstacles when implementing the solution?A: Yes we did run into some obstacles. One of the key show stoppers was the issue with portlet to portal communication. The GIS viewer (portlet) needed information to be passed  to and from Permit LA (Portal), but we were able to get everything configured and up and working quickly! Q: Was there a lot of custom work that needed to be done for this particular solution?A: We have done some customizations where workflows/ Task flows are involved.  Q: What do you think were the keys to success for rolling out WebCenter?A: Having a service oriented architecture and using portlets have been the key areas for rolling out Oracle WebCenter at LADBS. The Oracle WebCenter Content integration allows the flexibility to business users to maintain the content, which has really cut down on the reliance of IT, and employee productivity has increased as a result. If you missed the webcast, be sure to catch the replay to see a live demonstration of WebCenter in action! Los Angeles Department of Building & Safety Lowers Customer Service Costs with Oracle WebCenter from Oracle WebCenter

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• SQL SERVER – DMV – sys.dm_os_wait_stats Explanation – Wait Type – Day 3 of 28

  - by pinaldave

  The key Dynamic Management View (DMV) that helps us to understand wait stats is sys.dm_os_wait_stats; this DMV gives us all the information that we need to know regarding wait stats. However, the interpretation is left to us. This is a challenge as understanding wait stats can often be quite tricky. Anyway, we will cover few wait stats in one of the future articles. Today we will go over the basic understanding of the DMV. The Official Book OnLine Reference for DMV is over here: sys.dm_os_wait_stats. I suggest you all to refer this for all the accuracy. Following is a statement from the online book: “Specific types of wait times during query execution can indicate bottlenecks or stall points within the query. Similarly, high wait times, or wait counts server wide can indicate bottlenecks or hot spots in interaction query interactions within the server instance.” This is the statement which has inspired me to write this series. Let us first run the following statement from DMV. SELECT * FROM sys.dm_os_wait_stats ORDER BY wait_time_ms DESC GO Above statement will show us few of the columns. Here it is quick explanation of each of the column. wait_type – this is the name of the wait type. There can be three different kinds of wait types – resource, queue and external. waiting_tasks_count – this incremental counter is a good indication of frequent the wait is happening. If this number is very high, it is good indication for us to investigate that particular wait type. It is quite possible that the wait time is considerably low, but the frequency of the wait is much high. wait_time_ms – this is total wait accumulated for any type of wait. This is the total wait time and includes singal_wait_time_ms. max_wait_time_ms – this indicates the maximum wait type ever occurred for that particular wait type. Using this, one can estimate the intensity of the wait type in past. Again, it is not necessary that this max wait time will occur every time; so do not over invest yourself here. signal_wait_time_ms – this is the wait time when thread is marked as runnable and it gets to the running state. If the runnable queue is very long, you will find that this wait time becomes high. Additionally, please note that this DMV does not show current wait type or wait stats. This is cumulative view of the all the wait stats since server (instance) restarted or wait stats have been cleared. In future blog post, we will also cover two more DMVs which can be helpful to identify wait-related issues. ?sys.dm_os_waiting_tasks sys.dm_exec_requests Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL DMV, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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• How to prepare for an interview presentation!

  - by Tim Koekkoek

  During an interview process you might be asked to prepare a presentation as one of the steps in the recruitment process. Below, we want to give you some tips to help you prepare for what might be considered a daunting aspect of a recruitment process. Main purpose of the presentation Always keep in mind the main purpose of what the presentation is meant to convey. Generally speaking, an interview presentation is for the company to check if you have the ability to represent and sell the organization (and yourself), to the internal and external stakeholders in the position you are applying for. A presentation is often also part of the recruitment process to check whether you can structure and explain your experience and thoughts in a convincing manner. If you are unsure about the purpose of the presentation, feel free to ask your recruiter for more information. Preparation As with every task you do, preparation is key, so is the case with an interview presentation. It is important to know who your audience is. You have to adapt your presentation to your audience, ensuring that you are presenting the facts which they would want to hear. Furthermore, make sure you practice your presentation beforehand; this will make you more confident in your presenting skills. Also, estimate the length of your presentation as presentations or pitches during the recruitment process are often capped to a certain time limit. Structure Every presentation should have a beginning, middle and an end. Make sure you give an overview of your presentation and tell the audience what they can expect. Your presentation should have a logical order and a clear message. Always build up to your key message with strong arguments and evidence. When speaking about the topic, make sure you convey your points with conviction. Also be sure you believe the message you bring forward, if you don’t believe it yourself, then the audience definitely won’t! Delivery When you think back on successful presentations you have seen, the presenter was most likely always standing up. So if asked to do a presentation, follow this example and make sure you stand up as well. Standing up when you are doing your presentation shows confidence and control. Another important aspect in the delivery of the presentation is to relax and speak slowly and with enough volume for the audience to hear you. Speaking slowly allows the audience the time to absorb the information you are providing to them. Visual Using PowerPoint, or an equivalent, makes it very easy to have a visually attractive presentation. Make sure however that you take into account that the visual aids you use are there to support you, not for you to read word for word what is on the slides! Questions When starting your presentation, it is a good idea to tell your audience that you will deal with any questions they might have at the end of the presentation. This way it doesn’t interrupt your train of thought and the flow of your presentation. Answering questions at the end may give you additional opportunities to further expand on your facts in the topic. Some people might play the “devil’s advocate” role and confront you with opposing opinions, if this is the case, take your time to reiterate your points and remain professional in your response. A good way to deal with this is to start interacting with other members of the audience and ask for their opinions, so it will become a group discussion. This will also shows strong leadership skills, as you are open to discuss and ask for other opinions. If you are interested in more tips and tricks for your interview process, have a look at Competency Based Interview Tips and How to prepare for a Telephone Interview. For more information about Oracle and our vacancies, please visit our Facebook community and our careers website.

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• To sample or not to sample...

  - by [email protected]

  Ideally, we would know the exact answer to every question. How many people support presidential candidate A vs. B? How many people suffer from H1N1 in a given state? Does this batch of manufactured widgets have any defective parts? Knowing exact answers is expensive in terms of time and money and, in most cases, is impractical if not impossible. Consider asking every person in a region for their candidate preference, testing every person with flu symptoms for H1N1 (assuming every person reported when they had flu symptoms), or destructively testing widgets to determine if they are "good" (leaving no product to sell). Knowing exact answers, fortunately, isn't necessary or even useful in many situations. Understanding the direction of a trend or statistically significant results may be sufficient to answer the underlying question: who is likely to win the election, have we likely reached a critical threshold for flu, or is this batch of widgets good enough to ship? Statistics help us to answer these questions with a certain degree of confidence. This focuses on how we collect data. In data mining, we focus on the use of data, that is data that has already been collected. In some cases, we may have all the data (all purchases made by all customers), in others the data may have been collected using sampling (voters, their demographics and candidate choice). Building data mining models on all of your data can be expensive in terms of time and hardware resources. Consider a company with 40 million customers. Do we need to mine all 40 million customers to get useful data mining models? The quality of models built on all data may be no better than models built on a relatively small sample. Determining how much is a reasonable amount of data involves experimentation. When starting the model building process on large datasets, it is often more efficient to begin with a small sample, perhaps 1000 - 10,000 cases (records) depending on the algorithm, source data, and hardware. This allows you to see quickly what issues might arise with choice of algorithm, algorithm settings, data quality, and need for further data preparation. Instead of waiting for a model on a large dataset to build only to find that the results don't meet expectations, once you are satisfied with the results on the initial sample, you can  take a larger sample to see if model quality improves, and to get a sense of how the algorithm scales to the particular dataset. If model accuracy or quality continues to improve, consider increasing the sample size. Sampling in data mining is also used to produce a held-aside or test dataset for assessing classification and regression model accuracy. Here, we reserve some of the build data (data that includes known target values) to be used for an honest estimate of model error using data the model has not seen before. This sampling transformation is often called a split because the build data is split into two randomly selected sets, often with 60% of the records being used for model building and 40% for testing. Sampling must be performed with care, as it can adversely affect model quality and usability. Even a truly random sample doesn't guarantee that all values are represented in a given attribute. This is particularly troublesome when the attribute with omitted values is the target. A predictive model that has not seen any examples for a particular target value can never predict that target value! For other attributes, values may consist of a single value (a constant attribute) or all unique values (an identifier attribute), each of which may be excluded during mining. Values from categorical predictor attributes that didn't appear in the training data are not used when testing or scoring datasets. In subsequent posts, we'll talk about three sampling techniques using Oracle Database: simple random sampling without replacement, stratified sampling, and simple random sampling with replacement.

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• Speed up SQL Server queries with PREFETCH

  - by Akshay Deep Lamba

  Problem The SAN data volume has a throughput capacity of 400MB/sec; however my query is still running slow and it is waiting on I/O (PAGEIOLATCH_SH). Windows Performance Monitor shows data volume speed of 4MB/sec. Where is the problem and how can I find the problem? Solution This is another summary of a great article published by R. Meyyappan at www.sqlworkshops.com.  In my opinion, this is the first article that highlights and explains with working examples how PREFETCH determines the performance of a Nested Loop join.  First of all, I just want to recall that Prefetch is a mechanism with which SQL Server can fire up many I/O requests in parallel for a Nested Loop join. When SQL Server executes a Nested Loop join, it may or may not enable Prefetch accordingly to the number of rows in the outer table. If the number of rows in the outer table is greater than 25 then SQL will enable and use Prefetch to speed up query performance, but it will not if it is less than 25 rows. In this section we are going to see different scenarios where prefetch is automatically enabled or disabled. These examples only use two tables RegionalOrder and Orders.  If you want to create the sample tables and sample data, please visit this site www.sqlworkshops.com. The breakdown of the data in the RegionalOrders table is shown below and the Orders table contains about 6 million rows. In this first example, I am creating a stored procedure against two tables and then execute the stored procedure.  Before running the stored proceudre, I am going to include the actual execution plan. --Example provided by www.sqlworkshops.com --Create procedure that pulls orders based on City --Do not forget to include the actual execution plan CREATE PROC RegionalOrdersProc @City CHAR(20) AS BEGIN DECLARE @OrderID INT, @OrderDetails CHAR(200) SELECT @OrderID = o.OrderID, @OrderDetails = o.OrderDetails       FROM RegionalOrders ao INNER JOIN Orders o ON (o.OrderID = ao.OrderID)       WHERE City = @City END GO SET STATISTICS time ON GO --Example provided by www.sqlworkshops.com --Execute the procedure with parameter SmallCity1 EXEC RegionalOrdersProc 'SmallCity1' GO After running the stored procedure, if we right click on the Clustered Index Scan and click Properties we can see the Estimated Numbers of Rows is 24.    If we right click on Nested Loops and click Properties we do not see Prefetch, because it is disabled. This behavior was expected, because the number of rows containing the value ‘SmallCity1’ in the outer table is less than 25.   Now, if I run the same procedure with parameter ‘BigCity’ will Prefetch be enabled? --Example provided by www.sqlworkshops.com --Execute the procedure with parameter BigCity --We are using cached plan EXEC RegionalOrdersProc 'BigCity' GO As we can see from the below screenshot, prefetch is not enabled and the query takes around 7 seconds to execute. This is because the query used the cached plan from ‘SmallCity1’ that had prefetch disabled. Please note that even if we have 999 rows for ‘BigCity’ the Estimated Numbers of Rows is still 24.   Finally, let’s clear the procedure cache to trigger a new optimization and execute the procedure again. DBCC freeproccache GO EXEC RegionalOrdersProc 'BigCity' GO This time, our procedure runs under a second, Prefetch is enabled and the Estimated Number of Rows is 999.   The RegionalOrdersProc can be optimized by using the below example where we are using an optimizer hint. I have also shown some other hints that could be used as well. --Example provided by www.sqlworkshops.com --You can fix the issue by using any of the following --hints --Create procedure that pulls orders based on City DROP PROC RegionalOrdersProc GO CREATE PROC RegionalOrdersProc @City CHAR(20) AS BEGIN DECLARE @OrderID INT, @OrderDetails CHAR(200) SELECT @OrderID = o.OrderID, @OrderDetails = o.OrderDetails       FROM RegionalOrders ao INNER JOIN Orders o ON (o.OrderID = ao.OrderID)       WHERE City = @City       --Hinting optimizer to use SmallCity2 for estimation       OPTION (optimize FOR (@City = 'SmallCity2'))       --Hinting optimizer to estimate for the currnet parameters       --option (recompile)       --Hinting optimize not to use histogram rather       --density for estimation (average of all 3 cities)       --option (optimize for (@City UNKNOWN))       --option (optimize for UNKNOWN) END GO Conclusion, this tip was mainly aimed at illustrating how Prefetch can speed up query execution and how the different number of rows can trigger this.

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• Part 9: EBS Customizations, how to track

  - by volker.eckardt(at)oracle.com

  In the previous blogs we were concentrating on the preparation tasks. We have defined standards, we know about the tools and techniques we will start with. Additionally, we have defined the modification strategy, and how to handle such topics best. Now we are ready to take the requirements! Such requirements coming over in spreadsheets, word files (like GAP documents), or in any other format. As we have to assign some attributes, we start numbering all that and assign a short name to each of these requirements (=CEMLI reference). We may also have already a Functional person assigned, and we might involve someone from the tech team to estimate, and we like to assign a status such as 'planned', 'estimated' etc. All these data are usually kept in spreadsheets, but I would put them into a database (yes, I am from Oracle :). If you don't have any good looking and centralized application already, please give a try with Oracle APEX. It should be up and running in a day and the imported sheets are than manageable concurrently!  For one of my clients I have created this CEMLI-DB; in between enriched with a lot of additional functionality, but initially it was just a simple centralized CEMLI tracking application. Why I am pointing out again the centralized method to manage such data? Well, your data quality will dramatically increase, if you let your project members see (also review and update) "your" data.  APEX allows you to filter, sort, print, and also export. And if you can spend some time to define proper value lists, everyone will gain from. APEX allows you to work in 'agile' mode, means you can improve your application step by step. Let's say you like to reference a document, or even upload the same, you can do that. Or, you need to classify the CEMLIs by release, just add this release field, same for business area or CEMLI type. One CEMLI record may then look like this: Prepare one or two (online) reports, to be ready to present your "workload" to the project management. Use such extracts also when you work offline (to prioritize etc.). But as soon as you are again connected, feed the data back into the central application. Note: I have combined this application with an additional issue tracker.  Here the most important element is the CEMLI reference, which acts as link to any other application (if you are not using APEX also as issue tracker :).  Please spend a minute to define such a reference (see blog Part 8: How to name Customizations).   Summary: Building the bridge from Gap analyse to the development has to be done in a controlled way. Usually the information is provided differently, but it is suggested to collect all requirements centrally. Oracle APEX is a great solution to enter and maintain such information in a structured, but flexible way. APEX helped me a lot to work with distributed development teams during the complete development cycle.

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• The SmartAssembly Rearchitecture

  - by Simon Cooper

  You may have noticed that not a lot has happened to SmartAssembly in the past few months. However, the team has been very busy behind the scenes working on an entirely new version of SmartAssembly. SmartAssembly 6.5 Over the past few releases of SmartAssembly, the team had come to the realisation that the current 'architecture' - grown organically, way before RedGate bought it, from a simple name obfuscator over the years into a full-featured obfuscator and assembly instrumentation tool - was simply not up to the task. Not for what we wanted to do with it at the time, and not what we have planned for the future. Not only was it not up to what we wanted it to do, but it was severely limiting our development capabilities; long-standing bugs in the root architecture that couldn't be fixed, some rather...interesting...design decisions, and convoluted logic that increased the complexity of any bugfix or new feature tenfold. So, we set out to fix this. Earlier this year, a new engine was written on which SmartAssembly would be based. Over the following few months, each feature was ported over to the new engine and extensively tested by our existing unit and integration tests. The engine was linked into the existing UI (no easy task, due to the tight coupling between the UI and old engine), and existing RedGate products were tested on the new SmartAssembly to ensure the new engine acted in the same way. The result is SmartAssembly 6.5. The risks of a rearchitecture Are there risks to rearchitecting a product like SmartAssembly? Of course. There was a lot of undocumented behaviour in the old engine, and as part of the rearchitecture we had to find this behaviour, define it, and document it. In the process we found some behaviour of the old engine that simply did not make sense; hence the changes in pruning & obfuscation behaviour in the release notes. All the special edge cases we had to find, document, and re-implement. There was a chance that these special cases would not be found until near the end of the project, when everything is functionally complete and interacting together. By that stage, it would be hard to go back and change anything without a whole lot of extra work, delaying the release by months. We always knew this was a possibility; our initial estimate of the time required was '4 months, ± 4 months'. And that was including various mitigation strategies to reduce the likelihood of these issues being found right at the end. Fortunately, this worst-case did not happen. However, the rearchitecture did produce some benefits. As well as numerous bug fixes that we could not fix any other way, we've also added logging that lets you find out exactly why a particular field or property wasn't pruned or obfuscated. There's a new command line interface, we've tested it with WP7.1 and Silverlight 5, and we've added a new option to error reporting to improve the performance of instrumented apps by ~10%, at the cost of inaccurate line numbers in reports. So? What differences will I see? Largely none. SmartAssembly 6.5 produces the same output as SmartAssembly 6.2. The performance of 6.5 will be much faster for some users, and generally the same as 6.2 for the remaining. If you've encountered a bug with previous versions of SmartAssembly, I encourage you to try 6.5, as it has most likely been fixed in the rearchitecture. If you encounter a bug with 6.5, please do tell us; we'll be doing another release quite soon, so we'll aim to fix any issues caused by 6.5 in that release. Most importantly, the new architecture finally allows us to implement some Big Things with SmartAssembly we've been planning for many months; these will fundamentally change how you build, release and monitor your application. Stay tuned for further updates!

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• Planning development when academic research is involved

  - by Another Anonymous User

  Dear fellow programmers, how do you do "software planning" when academic research is involved? And, on a side note, how do you convince your boss that writing software is not like building a house and it's more like writing a novel? The gory details are below. I am in charge of a small dev team working in a research lab. We started developing a software with the purpose of going public one day (i.e. sell and make money off that). Such software depends on, amongst other things, at least two independent research lines: that is, there are at least two Ph.D. candidates that will, hopefully, one day come out with a working implementation of what we need. The main software depends also on other, more concrete resources that we as developers can take care of: graphics rendering, soft bodies deformation, etc. My boss asked me to write the specifications, requirements AND a bloody GANTT chart of the entire project. Faced with the fact that I don't have a clue about the research part, and that such research is fundamental for the software, he said "make assumptions." For the clarity of the argument, he is a professor whose Ph.D. students should come up with the research we need. And he comes from a strictly engineering background: plan everything first, write down specifications and only then write down code that "it's the last part". What I am doing now: I broke down the product in features; each 'feature' is, de facto, a separate product; Each feature is built on top of the previous one; Once a feature (A) has a working prototype the team can start working on the next feature (B), while QA for is being done for A (if money allows, more people can be brought in, etc.); Features that depend on research will come last: by then, hopefully, the research part will be completed (when is still a big question) ; Also, I set the team to use SCRUM for the development of 'version 1.0', due in a few months. This deadline could be set based on reasonable assumptions: we listed all required features, we counted our availability, and we gave a reasonable estimate. So my questions, again, are: How do I make my boss happy while at the same time get something out the door? How do I write specifications for something we -the developers- have no clue whether it's possible to do or not? (We still haven't decided which libraries to use for some tasks; we'll do so when we'll need to) How do I get the requirements for that, given that there are yet no clients nor investors, just lots of interests and promises? How do I get peace in the world? I am sure at least one of my questions will be answered :) ps: I am writing this anonymously since a potential investor might backfire if this is discovered. Hope you'll understand. However I must say I do not like this mentality of 'hiding the truth': this program will likely benefit many, and not being able to talk openly about this (with my name and my reputation attached) feels like censorship. But alas, I care more about your suggestions now.

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• A developer&rsquo;s WBS &ndash; 3 factors of 5

  - by johndoucette

  As a development manager, I have requested work breakdown structures (WBS) many times from the dev leads. Everyone has their own approach and why it takes sometimes days to get this simple list is often frustrating. Here is a simple way to get that elusive WBS done in 30 minutes and have 125 items in your list – well, 126. The WBS is made up of parent-child entities representing the overall outcome of the project. At the bottom of the hierarchical list should be the task item that a developer would perform in support of the branch in the list or WBS. Because I work with different dev leads on every project, I always ask the “what time value would you like to see at the lowest task in order to assign it to a developer and ensure it gets done within the timeframe”. I am particular to a task being 8 hours. Some like 8 to 24 hours. Stay away from tasks defaulting to 1 week. The task becomes way to vague and hard to manage completeness, especially on short budgets. As a developer, your focus is identifying the tasks you to accomplish in order to deliver the product. As a project manager, you will take the developer's WBS and add all the “other stuff” like quality testing, meetings, documentation, transition to maintenance, etc… Start your exercise with the name of the product you are delivering as a result of the project. You should be able to represent what you are building and deploying with one to three words. Example; XYZ Public Website Middleware BizTalk Application The reason you start with that single identifier is to always see the list as the product. It helps during each of the next three passes. Now, choose 5 tasks which in their entirety represent the product you will be delivering and add them to list under the product name you created earlier; Public Website     Security     Sites     Infrastructure     Publishing     Creative Continue this concept of seeing the list as the complete picture and decompose it one more level. You should have 25 items. Public Website     Security         Authentication         Login Control         Administration         DRM         Workflow     Sites         Masterpages         Page Layouts         Web Parts (RIA, Multimedia)         Content Types         Structures     Infrastructure         ...     Publishing         ...     Creative         ... And one more time for a total of 125 items. The top item makes the list 126. Public Website     Security         Authentication             Install (AD/ADAM/LDAP/SQL)             Configuration             Management             Web App Configuration             Implement Provider         Login Control             Login Form             Login/Logoff             pw change             pw recover/forgot             email verification         Administration             ...         DRM             ...         Workflow             ...     Sites         Masterpages         Page Layouts         Web Parts (RIA, Multimedia)         Content Types         Structures     Infrastructure         ...     Publishing         ...     Creative         ... The next step is to make sure the task at the bottom of every branch represents the “time value” you planned for the project. You can add more to the WBS and of course if you can’t find 5 items, 4 is fine. If a task can be done in a fraction of the time value you determined for the project, try to roll it up into a larger task. In the task actions (later when the iteration is being planned), decompose the details back to the simple tasks. Now, go estimate!

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• Web Developer - How to enhance my skillset?

  - by atif089

  First of all pardon my English. I am not a native English speaker I have been a Web Developer for the past 4 years. In these 4 years I have spent my time on the internet to learn things. My current skillset comprises of HTML CSS PHP MySQL jQuery (I would not say js and rather say jQuery because I am good at using jQuery and bad with plain javascript.) The above things seemed like an easier part of my life as I quickly learned them. But now I would really like to enhance my skillset and I am pretty confused which way to move ahead considering that I have to learn things using the web and references on my own. Design My first option is towards design. Shall I get started with design and start using Adobe Illustrator, Photoshop, Flash, Flex. Designing along with my previous skills looks like a money maker to me. As both are co-related to each other when web design is considered. And its easier to learn the first 2 and I hope I can get tutorials for the last 2 as well. Marketing A lot of my existing clients asked me if I do SEO. So this looked as a good field to me as well. I cannot estimate the scope of SEO but I assume it has a long future. Since I am business minded as well and there are a lot of tutorials around, should I start with SEO, SEM, Social Media, PPC or whatever it consists of. Software Development The complex plight and hardest thing (perhaps) but the easiest way to find a decent job in my location. If I go for software development what platform should be that I should be ideally going after? Should it be C# for windows development, or ASP.NET (once again enhances my skill set), J2EE (there are a lot of jobs for J2EE developers here) or plain C and C++. Also I think it is difficult to learn software languages right from Hello World, using internet? I have no clue how I learned PHP but I am sort of a pro now, but these other languages seems like a disaster to me? I cant figure out the reason if its because PHP is easier or there was a lot of tutorials around for PHP. Anyways is it also possible to learn software development right from Hello World using the web? Database / Server (Linux) / Network Administration Seems like a job with a decent pay but less number of jobs and a bit harder to learn online. (not sure) What should be the right track I should move ahead. P.S - Age is not a constraint for me as I am between 20-21, and I come from an IT background. I know quite little basics about C (upto structures) C++ (upto objects, I was not able to understand templates) Core Java (some basics and OOP concept) RDBMS Visual Basic 6 (used to do this long back) UNIX (a bunch of commands like who, finger, chmod, ls and a bit of #bash) Or is there anything else that I left out? I need you guys to please give me a feedback and the reason why I should select that field.

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• What is a good design pattern / lib for iOS 5 to synchronize with a web service?

  - by Junto

  We are developing an iOS application that needs to synchronize with a remote server using web services. The existing web services have an "operations" style rather than REST (implemented in WCF but exposing JSON HTTP endpoints). We are unsure of how to structure the web services to best fit with iOS and would love some advice. We are also interested in how to manage the synchronization process within iOS. Without going into detailed specifics, the application allows the user to estimate repair costs at a remote site. These costs are broken down by room and item. If the user has an internet connection this data can be sent back to the server. Multiple photographs can be taken of each item, but they will be held in a separate queue, which sends when the connection is optimal (ideally wifi). Our backend application controls the unique ids for each room and item. Thus, each time we send these costs to the server, the server echoes the central database ids back, thus, that they can be synchronized in the mobile app. I have simplified this a little, since the operations contract is actually much larger, but I just want to illustrate the basic requirements without complicating matters. Firstly, the web service architecture: We currently have two operations: GetCosts and UpdateCosts. My assumption is that if we used a strict REST architecture we would need to break our single web service operations into multiple smaller services. This would make the services much more chatty and we would also have to guarantee a delivery order from the app. For example, we need to make sure that containing rooms are added before the item. Although this seems much more RESTful, our perception is that these extra calls are expensive connections (security checks, database calls, etc). Does the type of web api (operation over service focus) determine chunky vs chatty? Since this is mobile (3G), are we better handling lots of smaller messages, or a few large ones? Secondly, the iOS side. What is the current advice on how to manage data synchronization within the iOS (5) app itself. We need multiple queues and we need to guarantee delivery order in each queue (and technically, ordering between queues). The server needs to control unique ids and other properties and echo them back to the application. The application then needs to update an internal database and when re-updating, make sure the correct ids are available in the update message (essentially multiple inserts and updates in one call). Our backend has a ton of business logic operating on these cost estimates. We don't want any of this in the app itself. Currently the iOS app sends the cost data, and then the server echoes that data back with populated ids (and other data). The existing cost data is deleted and the echoed response data is added to the client database on the device. This is causing us problems, because any photos might not have been sent, but the original entity tree has been removed and replaced. Obviously updating the costs tree rather than replacing it would remove this problem, but I'm not sure if there are any nice xcode libraries out there to do such things. I welcome any advice you might have.

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• How much is a subscriber worth?

  - by Tom Lewin

  This year at Red Gate, we’ve started providing a way to back up SQL Azure databases and Azure storage. We decided to sell this as a service, instead of a product, which means customers only pay for what they use. Unfortunately for us, it makes figuring out revenue much trickier. With a product like SQL Compare, a customer pays for it, and it’s theirs for good. Sure, we offer support and upgrades, but, fundamentally, the sale is a simple, upfront transaction: we’ve made this product, you need this product, we swap product for money and everyone is happy. With software as a service, it isn’t that easy. The money and product don’t change hands up front. Instead, we provide a service in exchange for a recurring fee. We know someone buying SQL Compare will pay us $X, but we don’t know how long service customers will stay with us, or how much they will spend. How do we find this out? We use lifetime value analysis. What is lifetime value? Lifetime value, or LTV, is how much a customer is worth to the business. For Entrepreneurs has a brilliant write up that we followed to conduct our analysis. Basically, it all boils down to this equation: LTV = ARPU x ALC To make it a bit less of an alphabet-soup and a bit more understandable, we can write it out in full: The lifetime value of a customer equals the average revenue per customer per month, times the average time a customer spends with the service Simple, right? A customer is worth the average spend times the average stay. If customers pay on average $50/month, and stay on average for ten months, then a new customer will, on average, bring in $500 over the time they are a customer! Average spend is easy to work out; it’s revenue divided by customers. The problem comes when we realise that we don’t know exactly how long a customer will stay with us. How can we figure out the average lifetime of a customer, if we only have six months’ worth of data? The answer lies in the fact that: Average Lifetime of a Customer = 1 / Churn Rate The churn rate is the percentage of customers that cancel in a month. If half of your customers cancel each month, then your average customer lifetime is two months. The problem we faced was that we didn’t have enough data to make an estimate of one month’s cancellations reliable (because barely anybody cancels)! To deal with this data problem, we can take data from the last three months instead. This means we have more data to play with. We can still use the equation above, we just need to multiply the final result by three (as we worked out how many three month periods customers stay for, and we want our answer to be in months). Now these estimates are likely to be fairly unreliable; when there’s not a lot of data it pays to be cautious with inference. That said, the numbers we have look fairly consistent, and it’s super easy to revise our estimates when new data comes in. At the very least, these numbers give us a vague idea of whether a subscription business is viable. As far as Cloud Services goes, the business looks very viable indeed, and the low cancellation rates are much more than just data points in LTV equations; they show that the product is working out great for our customers, which is exactly what we’re looking for!

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• Planning development when academic research is involved

  - by Another Anonymous User

  Dear fellow programmers, how do you do "software planning" when academic research is involved? And, on a side note, how do you convince your boss that writing software is not like building a house and it's more like writing a novel? The gory details are below. I am in charge of a small dev team working in a research lab. We started developing a software with the purpose of going public one day (i.e. sell and make money off that). Such software depends on, amongst other things, at least two independent research lines: that is, there are at least two Ph.D. candidates that will, hopefully, one day come out with a working implementation of what we need. The main software depends also on other, more concrete resources that we as developers can take care of: graphics rendering, soft bodies deformation, etc. My boss asked me to write the specifications, requirements AND a bloody GANTT chart of the entire project. Faced with the fact that I don't have a clue about the research part, and that such research is fundamental for the software, he said "make assumptions." For the clarity of the argument, he is a professor whose Ph.D. students should come up with the research we need. And he comes from a strictly engineering background: plan everything first, write down specifications and only then write down code that "it's the last part". What I am doing now: I broke down the product in features; each 'feature' is, de facto, a separate product; Each feature is built on top of the previous one; Once a feature (A) has a working prototype the team can start working on the next feature (B), while QA for is being done for A (if money allows, more people can be brought in, etc.); Features that depend on research will come last: by then, hopefully, the research part will be completed (when is still a big question) ; Also, I set the team to use SCRUM for the development of 'version 1.0', due in a few months. This deadline could be set based on reasonable assumptions: we listed all required features, we counted our availability, and we gave a reasonable estimate. So my questions, again, are: How do I make my boss happy while at the same time get something out the door? How do I write specifications for something we -the developers- have no clue whether it's possible to do or not? (We still haven't decided which libraries to use for some tasks; we'll do so when we'll need to) How do I get the requirements for that, given that there are yet no clients nor investors, just lots of interests and promises? How do I get peace in the world? I am sure at least one of my questions will be answered :) ps: I am writing this anonymously since a potential investor might backfire if this is discovered. Hope you'll understand. However I must say I do not like this mentality of 'hiding the truth': this program will likely benefit many, and not being able to talk openly about this (with my name and my reputation attached) feels like censorship. But alas, I care more about your suggestions now.

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• Approach for packing 2D shapes while minimizing total enclosing area

  - by Dennis

  Not sure on my tags for this question, but in short .... I need to solve a problem of packing industrial parts into crates while minimizing total containing area. These parts are motors, or pumps, or custom-made components, and they have quite unusual shapes. For some, it may be possible to assume that a part === rectangular cuboid, but some are not so simple, i.e. they assume a shape more of that of a hammer or letter T. With those, (assuming 2D shape), by alternating direction of top & bottom, one can pack more objects into the same space, than if all tops were in the same direction. Crude example below with letter "T"-shaped parts: ***** xxxxx ***** x ***** *** ooo * x vs * x vs * x vs * x o * x * xxxxx * x * x o xxxxx xxx Right now we are solving the problem by something like this: using CAD software, make actual models of how things fit in crate boxes make estimates of actual crate dimensions & write them into Excel file (1) is crazy amount of work and as the result we have just a limited amount of possible entries in (2), the Excel file. The good things is that programming this is relatively easy. Given a combination of products to go into crates, we do a lookup, and if entry exists in the Excel (or Database), we bring it out. If it doesn't, we say "sorry, no data!". I don't necessarily want to go full force on making up some crazy algorithm that given geometrical part description can align, rotate, and figure out best part packing into a crate, given its shape, but maybe I do.. Question Well, here is my question: assuming that I can represent my parts as 2D (to be determined how), and that some parts look like letter T, and some parts look like rectangles, which algorithm can I use to give me a good estimate on the dimensions of the encompassing area, while ensuring that the parts are packed in a minimal possible area, to minimize crating/shipping costs? Are there approximation algorithms? Seeing how this can get complex, is there an existing library I could use? My thought / Approach My naive approach would be to define a way to describe position of parts, and place the first part, compute total enclosing area & dimensions. Then place 2nd part in 0 degree orientation, repeat, place it at 180 degree orientation, repeat (for my case I don't think 90 degree rotations will be meaningful due to long lengths of parts). Proceed using brute force "tacking on" other parts to the enclosing area until all parts are processed. I may have to shift some parts a tad (see 3rd pictorial example above with letters T). This adds a layer of 2D complexity rather than 1D. I am not sure how to approach this. One idea I have is genetic algorithms, but I think those will take up too much processing power and time. I will need to look out for shape collisions, as well as adding extra padding space, since we are talking about real parts with irregularities rather than perfect imaginary blocks. I'm afraid this can get geometrically messy fairly fast, and I'd rather keep things simple, if I can. But what if the best (practical) solution is to pack things into different crate boxes rather than just one? This can get a bit more tricky. There is human element involved as well, i.e. like parts can go into same box and are thus a constraint to be considered. Some parts that are not the same are sometimes grouped together for shipping and can be considered as a common grouped item. Sometimes customers want things shipped their way, which adds human element to constraints. so there will have to be some customization.

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• ?12c database ????Adaptive Execution Plans ????????

  - by Liu Maclean(???)

  12c R1 ????SQL??????- Adaptive Execution Plans ????????,???????optimizer ??????(runtime)???????????????, ????????????????????? SQL???????? ????????????, ?????????????????????????????????????????????????????????????adaptive plan ????????????????????????????????????,?????subplan???????????????????? ??????, ???????? ???????????????,?????????, ?????? ???????????????”???”????, ???????????????????buffer ???????  ????????????,?????,??????????????????? ???optimizer ?????????????????????????,?????????????????????????????????????????plan???? ??12C?????????????, ???????????????????,?????? ???????????? ????????????2???: Dynamic Plans????: ???????????????????????;??????,???optimizer??????????subplans??????????????, ???????????????????,?????????????? Reoptimization????: ?Dynamic Plans????,Reoptimization??????????????????????Reoptimization??,?????????????????????????,??reoptimization????? OPTIMIZER_ADAPTIVE_REPORTING_ONLY ???? report-only????????????????TRUE,?????????report-only????,???????????????,??????????????? Dynamic Plans ??????????????,????????????????????????, ?????????????,???????????,????????????????????????????????????????? ?????????????final plan??????????????default plan, ??final plan?default plan???????,????????????? subplan ???????????????,???????????????????????? ??????,???????statistics collector ?buffer???????????statistics collector?????????????????,???????????????????????????? ?????????????????????????????????????????,??????????,?????????????? ???????????,???????buffer???? ???????????????,?????????????????????????????,??????buffer,??????final plan? ????????,???????????????????????,????????????????? ?V$SQL??????IS_RESOLVED_DYNAMIC_PLAN??????????final plan???default plan? ??????dynamic plan ???????SQL PLAN directives?????? declare cursor PLAN_DIRECTIVE_IDS is select directive_id from DBA_SQL_PLAN_DIRECTIVES; begin for z in PLAN_DIRECTIVE_IDS loop DBMS_SPD.DROP_SQL_PLAN_DIRECTIVE(z.directive_id); end loop; end; / explain plan for select /*MALCEAN*/ product_name from oe.order_items o, oe.product_information p where o.unit_price=15 and quantity>1 and p.product_id=o.product_id; select * from table(dbms_xplan.display()); Plan hash value: 1255158658 www.askmaclean.com ------------------------------------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | ------------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 4 | 128 | 7 (0)| 00:00:01 | | 1 | NESTED LOOPS | | | | | | | 2 | NESTED LOOPS | | 4 | 128 | 7 (0)| 00:00:01 | |* 3 | TABLE ACCESS FULL | ORDER_ITEMS | 4 | 48 | 3 (0)| 00:00:01 | |* 4 | INDEX UNIQUE SCAN | PRODUCT_INFORMATION_PK | 1 | | 0 (0)| 00:00:01 | | 5 | TABLE ACCESS BY INDEX ROWID| PRODUCT_INFORMATION | 1 | 20 | 1 (0)| 00:00:01 | ------------------------------------------------------------------------------------------------------- Predicate Information (identified by operation id): --------------------------------------------------- 3 - filter("O"."UNIT_PRICE"=15 AND "QUANTITY">1) 4 - access("P"."PRODUCT_ID"="O"."PRODUCT_ID") alter session set events '10053 trace name context forever,level 1'; OR alter session set events 'trace[SQL_Plan_Directive] disk highest'; select /*MALCEAN*/ product_name from oe.order_items o, oe.product_information p where o.unit_price=15 and quantity>1 and p.product_id=o.product_id; ---------------------------------------------------------------+-----------------------------------+ | Id | Operation | Name | Rows | Bytes | Cost | Time | ---------------------------------------------------------------+-----------------------------------+ | 0 | SELECT STATEMENT | | | | 7 | | | 1 | HASH JOIN | | 4 | 128 | 7 | 00:00:01 | | 2 | NESTED LOOPS | | | | | | | 3 | NESTED LOOPS | | 4 | 128 | 7 | 00:00:01 | | 4 | STATISTICS COLLECTOR | | | | | | | 5 | TABLE ACCESS FULL | ORDER_ITEMS | 4 | 48 | 3 | 00:00:01 | | 6 | INDEX UNIQUE SCAN | PRODUCT_INFORMATION_PK| 1 | | 0 | | | 7 | TABLE ACCESS BY INDEX ROWID | PRODUCT_INFORMATION | 1 | 20 | 1 | 00:00:01 | | 8 | TABLE ACCESS FULL | PRODUCT_INFORMATION | 1 | 20 | 1 | 00:00:01 | ---------------------------------------------------------------+-----------------------------------+ Predicate Information: ---------------------- 1 - access("P"."PRODUCT_ID"="O"."PRODUCT_ID") 5 - filter(("O"."UNIT_PRICE"=15 AND "QUANTITY">1)) 6 - access("P"."PRODUCT_ID"="O"."PRODUCT_ID") ===================================== SPD: BEGIN context at statement level ===================================== Stmt: ******* UNPARSED QUERY IS ******* SELECT /*+ OPT_ESTIMATE (@"SEL$1" JOIN ("P"@"SEL$1" "O"@"SEL$1") ROWS=13.000000 ) OPT_ESTIMATE (@"SEL$1" TABLE "O"@"SEL$1" ROWS=13.000000 ) */ "P"."PRODUCT_NAME" "PRODUCT_NAME" FROM "OE"."ORDER_ITEMS" "O","OE"."PRODUCT_INFORMATION" "P" WHERE "O"."UNIT_PRICE"=15 AND "O"."QUANTITY">1 AND "P"."PRODUCT_ID"="O"."PRODUCT_ID" Objects referenced in the statement PRODUCT_INFORMATION[P] 92194, type = 1 ORDER_ITEMS[O] 92197, type = 1 Objects in the hash table Hash table Object 92197, type = 1, ownerid = 6573730143572393221: No Dynamic Sampling Directives for the object Hash table Object 92194, type = 1, ownerid = 17822962561575639002: No Dynamic Sampling Directives for the object Return code in qosdInitDirCtx: ENBLD =================================== SPD: END context at statement level =================================== ======================================= SPD: BEGIN context at query block level ======================================= Query Block SEL$1 (#0) Return code in qosdSetupDirCtx4QB: NOCTX ===================================== SPD: END context at query block level ===================================== SPD: Return code in qosdDSDirSetup: NOCTX, estType = TABLE SPD: Generating finding id: type = 1, reason = 1, objcnt = 1, obItr = 0, objid = 92197, objtyp = 1, vecsize = 6, colvec = [4, 5, ], fid = 2896834833840853267 SPD: Inserted felem, fid=2896834833840853267, ftype = 1, freason = 1, dtype = 0, dstate = 0, dflag = 0, ver = YES, keep = YES SPD: qosdCreateFindingSingTab retCode = CREATED, fid = 2896834833840853267 SPD: qosdCreateDirCmp retCode = CREATED, fid = 2896834833840853267 SPD: Return code in qosdDSDirSetup: NOCTX, estType = TABLE SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = JOIN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SKIP_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = JOIN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Generating finding id: type = 1, reason = 1, objcnt = 1, obItr = 0, objid = 92197, objtyp = 1, vecsize = 6, colvec = [4, 5, ], fid = 2896834833840853267 SPD: Modified felem, fid=2896834833840853267, ftype = 1, freason = 1, dtype = 0, dstate = 0, dflag = 0, ver = YES, keep = YES SPD: Generating finding id: type = 1, reason = 1, objcnt = 1, obItr = 0, objid = 92194, objtyp = 1, vecsize = 2, colvec = [1, ], fid = 5618517328604016300 SPD: Modified felem, fid=5618517328604016300, ftype = 1, freason = 1, dtype = 0, dstate = 0, dflag = 0, ver = NO, keep = NO SPD: Generating finding id: type = 1, reason = 1, objcnt = 1, obItr = 0, objid = 92194, objtyp = 1, vecsize = 2, colvec = [1, ], fid = 1142802697078608149 SPD: Modified felem, fid=1142802697078608149, ftype = 1, freason = 1, dtype = 0, dstate = 0, dflag = 0, ver = NO, keep = NO SPD: Generating finding id: type = 1, reason = 2, objcnt = 2, obItr = 0, objid = 92194, objtyp = 1, vecsize = 0, obItr = 1, objid = 92197, objtyp = 1, vecsize = 0, fid = 1437680122701058051 SPD: Modified felem, fid=1437680122701058051, ftype = 1, freason = 2, dtype = 0, dstate = 0, dflag = 0, ver = NO, keep = NO select * from table(dbms_xplan.display_cursor(format=>'report')) ; ????report????adaptive plan Adaptive plan: ------------- This cursor has an adaptive plan, but adaptive plans are enabled for reporting mode only.  The plan that would be executed if adaptive plans were enabled is displayed below. ------------------------------------------------------------------------------------------ | Id  | Operation          | Name                | Rows  | Bytes | Cost (%CPU)| Time     | ------------------------------------------------------------------------------------------ |   0 | SELECT STATEMENT   |                     |       |       |     7 (100)|          | |*  1 |  HASH JOIN         |                     |     4 |   128 |     7   (0)| 00:00:01 | |*  2 |   TABLE ACCESS FULL| ORDER_ITEMS         |     4 |    48 |     3   (0)| 00:00:01 | |   3 |   TABLE ACCESS FULL| PRODUCT_INFORMATION |     1 |    20 |     1   (0)| 00:00:01 | ------------------------------------------------------------------------------------------ SQL> select SQL_ID,IS_RESOLVED_DYNAMIC_PLAN,sql_text from v$SQL WHERE SQL_TEXT like '%MALCEAN%' and sql_text not like '%like%'; SQL_ID IS -------------------------- -- SQL_TEXT -------------------------------------------------------------------------------- 6ydj1bn1bng17 Y select /*MALCEAN*/ product_name from oe.order_items o, oe.product_information p where o.unit_price=15 and quantity>1 and p.product_id=o.product_id ???? explain plan for ????default plan, ??????optimizer???final plan,??V$SQL.IS_RESOLVED_DYNAMIC_PLAN???Y,????????????? DBA_SQL_PLAN_DIRECTIVES?????????????SQL PLAN DIRECTIVES, ???12c? ???MMON?????DML ???column usage??????????,????SMON??? MMON????SGA??PLAN DIRECTIVES??? ?????DBMS_SPD.flush_sql_plan_directive???? select directive_id,type,reason from DBA_SQL_PLAN_DIRECTIVES / DIRECTIVE_ID TYPE REASON ----------------------------------- -------------------------------- ----------------------------- 10321283028317893030 DYNAMIC_SAMPLING JOIN CARDINALITY MISESTIMATE 4757086536465754886 DYNAMIC_SAMPLING JOIN CARDINALITY MISESTIMATE 16085268038103121260 DYNAMIC_SAMPLING JOIN CARDINALITY MISESTIMATE SQL> set pages 9999 SQL> set lines 300 SQL> col state format a5 SQL> col subobject_name format a11 SQL> col col_name format a11 SQL> col object_name format a13 SQL> select d.directive_id, o.object_type, o.object_name, o.subobject_name col_name, d.type, d.state, d.reason 2 from dba_sql_plan_directives d, dba_sql_plan_dir_objects o 3 where d.DIRECTIVE_ID=o.DIRECTIVE_ID 4 and o.object_name in ('ORDER_ITEMS') 5 order by d.directive_id; DIRECTIVE_ID OBJECT_TYPE OBJECT_NAME COL_NAME TYPE STATE REASON ------------ ------------ ------------- ----------- -------------------------------- ----- ------------------------------------- --- 1.8156E+19 COLUMN ORDER_ITEMS UNIT_PRICE DYNAMIC_SAMPLING NEW SINGLE TABLE CARDINALITY MISESTIMATE 1.8156E+19 TABLE ORDER_ITEMS DYNAMIC_SAMPLING NEW SINGLE TABLE CARDINALITY MISESTIMATE 1.8156E+19 COLUMN ORDER_ITEMS QUANTITY DYNAMIC_SAMPLING NEW SINGLE TABLE CARDINALITY MISESTIMATE DBA_SQL_PLAN_DIRECTIVES????? _BASE_OPT_DIRECTIVE ? _BASE_OPT_FINDING SELECT d.dir_own#, d.dir_id, d.f_id, decode(type, 1, 'DYNAMIC_SAMPLING', 'UNKNOWN'), decode(state, 1, 'NEW', 2, 'MISSING_STATS', 3, 'HAS_STATS', 4, 'CANDIDATE', 5, 'PERMANENT', 6, 'DISABLED', 'UNKNOWN'), decode(bitand(flags, 1), 1, 'YES', 'NO'), cast(d.created as timestamp), cast(d.last_modified as timestamp), -- Please see QOSD_DAYS_TO_UPDATE and QOSD_PLUS_SECONDS for more details -- about 6.5 cast(d.last_used as timestamp) - NUMTODSINTERVAL(6.5, 'day') FROM sys.opt_directive$ d ??dbms_spd??? SQL PLAN DIRECTIVES, SQL PLAN DIRECTIVES???retention ???53?: Package: DBMS_SPD This package provides subprograms for managing Sql Plan Directives(SPD). SPD are objects generated automatically by Oracle server. For example, if server detects that the single table cardinality estimated by optimizer is off from the actual number of rows returned when accessing the table, it will automatically create a directive to do dynamic sampling for the table. When any Sql statement referencing the table is compiled, optimizer will perform dynamic sampling for the table to get more accurate estimate. Notes: DBMSL_SPD is a invoker-rights package. The invoker requires ADMINISTER SQL MANAGEMENT OBJECT privilege for executing most of the subprograms of this package. Also the subprograms commit the current transaction (if any), perform the operation and commit it again. DBA view dba_sql_plan_directives shows all the directives created in the system and the view dba_sql_plan_dir_objects displays the objects that are included in the directives. -- Default value for SPD_RETENTION_WEEKS SPD_RETENTION_WEEKS_DEFAULT CONSTANT varchar2(4) := '53'; | STATE : NEW : Newly created directive. | : MISSING_STATS : The directive objects do not | have relevant stats. | : HAS_STATS : The objects have stats. | : PERMANENT : A permanent directive. Server | evaluated effectiveness and these | directives are useful. | | AUTO_DROP : YES : Directive will be dropped | automatically if not | used for SPD_RETENTION_WEEKS. | This is the default behavior. | NO : Directive will not be dropped | automatically. Procedure: flush_sql_plan_directive This procedure allows manually flushing the Sql Plan directives that are automatically recorded in SGA memory while executing sql statements. The information recorded in SGA are periodically flushed by oracle background processes. This procedure just provides a way to flush the information manually. ????”_optimizer_dynamic_plans”(enable dynamic plans)????????,???TRUE??DYNAMIC PLAN? ???FALSE???????????? ????,Dynamic Plan????????????Nested Loop?Hash Join???case ,????????Nested loop???????????HASH JOIN,?HASH JOIN????????????????? ????????subplan?????,???? pass?? ?join method???,?????STATISTICS COLLECTOR???cardinality?,???????HASH JOIN?????Nested Loop,????????????subplan?????access path; ???????Sales??????????????????,????HASH JOIN,??SUBPLAN??customers?????????;?????Nested Loop,???????cust_id?????Range Scan+Access by Rowid? Cardinality feedback Cardinality feedback????????11.2????,????????re-optimization???;  ???????????,Cardinality feedback?????????????????????????? ???????????????????,?????????????????,??????????Cardinality feedback????????????? ????????????????????????? ??????????????Cardinality feedback ??: ????????,???????????,??????????,????????????????selectivity ??? ????????????: ??????,?????????????????????????????????,??????????????????? ????????????????????????????????????????,?????????????????????????? ?????????,???????????????,?????????? ??????????Cardinality ????,??????join Cardinality ????????? Cardinality feedback???????cursor?,?Cursor???aged out????? SELECT /*+ gather_plan_statistics */ product_name FROM order_items o, product_information p WHERE o.unit_price = 15 AND quantity > 1 AND p.product_id = o.product_id Plan hash value: 1553478007 ---------------------------------------------------------------------------------------------------------------------------------------- | Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers | Reads | OMem | 1Mem | Used-Mem | ---------------------------------------------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 1 | | 13 |00:00:00.01 | 24 | 20 | | | | |* 1 | HASH JOIN | | 1 | 4 | 13 |00:00:00.01 | 24 | 20 | 2061K| 2061K| 429K (0)| |* 2 | TABLE ACCESS FULL| ORDER_ITEMS | 1 | 4 | 13 |00:00:00.01 | 7 | 6 | | | | | 3 | TABLE ACCESS FULL| PRODUCT_INFORMATION | 1 | 1 | 288 |00:00:00.01 | 17 | 14 | | | | ---------------------------------------------------------------------------------------------------------------------------------------- SELECT /*+ gather_plan_statistics */ product_name FROM order_items o, product_information p WHERE o.unit_price = 15 AND quantity > 1 AND p.product_id = o.product_id Plan hash value: 1553478007 ------------------------------------------------------------------------------------------------------------------------------- | Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers | OMem | 1Mem | Used-Mem | ------------------------------------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 1 | | 13 |00:00:00.01 | 24 | | | | |* 1 | HASH JOIN | | 1 | 13 | 13 |00:00:00.01 | 24 | 2061K| 2061K| 413K (0)| |* 2 | TABLE ACCESS FULL| ORDER_ITEMS | 1 | 13 | 13 |00:00:00.01 | 7 | | | | | 3 | TABLE ACCESS FULL| PRODUCT_INFORMATION | 1 | 288 | 288 |00:00:00.01 | 17 | | | | ------------------------------------------------------------------------------------------------------------------------------- Note ----- - statistics feedback used for this statement SQL> select count(*) from v$SQL where SQL_ID='cz0hg2zkvd10y'; COUNT(*) ---------- 2 SQL>select sql_ID,USE_FEEDBACK_STATS FROM V$SQL_SHARED_CURSOR where USE_FEEDBACK_STATS ='Y'; SQL_ID U ------------- - cz0hg2zkvd10y Y ????????Cardinality feedback????,???????????????????????????,????????????order_items???????? ????2??????plan hash value??(??????????),?????2????child cursor??????gather_plan_statistics???actual : A-ROWS  estimate :E-ROWS????????? Automatic Re-optimization ???dynamic plan, Re-optimization???????????????  ?  ??????????????? ????????????????????????????????  ???????????,??????????????, ???????????????????? ???????????  Re-optimization??, ????????????????????? Re-optimization????dynamic plan??????????  dynamic plan????????????????????, ???????????????????? ????,??????????join order ??????????????,?????????????join order????? ??????,????????Re-optimization, ??Re-optimization ??????????????????? ?Oracle database 12c?,join statistics?????????????????????,??????????????????????Re-optimization???????????adaptive cursor sharing????? ????????????????,???????????? ????? ???????statistics collectors ????????????????????Re-optimization??????2?????????????,???????????????? ??????????????Re-optimization?????,?????????????????????? ???v$SQL??????IS_REOPTIMIZABLE?????????????????????Re-optimization,??????????Re-optimization???,?????Re-optimization ,???????reporting????? IS_REOPTIMIZABLE VARCHAR2(1) This columns shows whether the next execution matching this child cursor will trigger a reoptimization. The values are:   Y: If the next execution will trigger a reoptimization R: If the child cursor contains reoptimization information, but will not trigger reoptimization because the cursor was compiled in reporting mode N: If the child cursor has no reoptimization information ??1: select plan_table_output from table (dbms_xplan.display_cursor('gwf99gfnm0t7g',NULL,'ALLSTATS LAST')); SQL_ID  gwf99gfnm0t7g, child number 0 ------------------------------------- SELECT /*+ SFTEST gather_plan_statistics */ o.order_id, v.product_name FROM  orders o,   ( SELECT order_id, product_name FROM order_items o, product_information p     WHERE  p.product_id = o.product_id AND list_price < 50 AND min_price < 40  ) v WHERE o.order_id = v.order_id Plan hash value: 1906736282 ------------------------------------------------------------------------------------------------------------------------------------------- | Id  | Operation             | Name                | Starts | E-Rows | A-Rows |   A-Time   | Buffers | Reads  |  OMem |  1Mem | Used-Mem | ------------------------------------------------------------------------------------------------------------------------------------------- |   0 | SELECT STATEMENT      |                     |      1 |        |    269 |00:00:00.02 |    1336 |     18 |       |       |          | |   1 |  NESTED LOOPS         |                     |      1 |      1 |    269 |00:00:00.02 |    1336 |     18 |       |       |          | |   2 |   MERGE JOIN CARTESIAN|                     |      1 |      4 |   9135 |00:00:00.02 |      34 |     15 |       |       |          | |*  3 |    TABLE ACCESS FULL  | PRODUCT_INFORMATION |      1 |      1 |     87 |00:00:00.01 |      33 |     14 |       |       |          | |   4 |    BUFFER SORT        |                     |     87 |    105 |   9135 |00:00:00.01 |       1 |      1 |  4096 |  4096 | 4096  (0)| |   5 |     INDEX FULL SCAN   | ORDER_PK            |      1 |    105 |    105 |00:00:00.01 |       1 |      1 |       |       |          | |*  6 |   INDEX UNIQUE SCAN   | ORDER_ITEMS_UK      |   9135 |      1 |    269 |00:00:00.01 |    1302 |      3 |       |       |          | ------------------------------------------------------------------------------------------------------------------------------------------- Predicate Information (identified by operation id): ---------------------------------------------------    3 - filter(("MIN_PRICE"<40 AND "LIST_PRICE"<50))    6 - access("O"."ORDER_ID"="ORDER_ID" AND "P"."PRODUCT_ID"="O"."PRODUCT_ID") SQL_ID  gwf99gfnm0t7g, child number 1 ------------------------------------- SELECT /*+ SFTEST gather_plan_statistics */ o.order_id, v.product_name FROM  orders o,   ( SELECT order_id, product_name FROM order_items o, product_information p     WHERE  p.product_id = o.product_id AND list_price < 50 AND min_price < 40  ) v WHERE o.order_id = v.order_id Plan hash value: 35479787 -------------------------------------------------------------------------------------------------------------------------------------------- | Id  | Operation              | Name                | Starts | E-Rows | A-Rows |   A-Time   | Buffers | Reads  |  OMem |  1Mem | Used-Mem | -------------------------------------------------------------------------------------------------------------------------------------------- |   0 | SELECT STATEMENT       |                     |      1 |        |    269 |00:00:00.01 |      63 |      3 |       |       |          | |   1 |  NESTED LOOPS          |                     |      1 |    269 |    269 |00:00:00.01 |      63 |      3 |       |       |          | |*  2 |   HASH JOIN            |                     |      1 |    313 |    269 |00:00:00.01 |      42 |      3 |  1321K|  1321K| 1234K (0)| |*  3 |    TABLE ACCESS FULL   | PRODUCT_INFORMATION |      1 |     87 |     87 |00:00:00.01 |      16 |      0 |       |       |          | |   4 |    INDEX FAST FULL SCAN| ORDER_ITEMS_UK      |      1 |    665 |    665 |00:00:00.01 |      26 |      3 |       |       |          | |*  5 |   INDEX UNIQUE SCAN    | ORDER_PK            |    269 |      1 |    269 |00:00:00.01 |      21 |      0 |       |       |          | -------------------------------------------------------------------------------------------------------------------------------------------- Predicate Information (identified by operation id): ---------------------------------------------------    2 - access("P"."PRODUCT_ID"="O"."PRODUCT_ID")    3 - filter(("MIN_PRICE"<40 AND "LIST_PRICE"<50))    5 - access("O"."ORDER_ID"="ORDER_ID") Note -----    - statistics feedback used for this statement    SQL> select IS_REOPTIMIZABLE,child_number FROM V$SQL  A where A.SQL_ID='gwf99gfnm0t7g'; IS CHILD_NUMBER -- ------------ Y             0 N             1    1* select child_number,other_xml From v$SQL_PLAN  where SQL_ID='gwf99gfnm0t7g' and other_xml is not nul SQL> / CHILD_NUMBER OTHER_XML ------------ --------------------------------------------------------------------------------            1 <other_xml><info type="cardinality_feedback">yes</info><info type="db_version">1              2.1.0.1</info><info type="parse_schema"><![CDATA["OE"]]></info><info type="plan_              hash">35479787</info><info type="plan_hash_2">3382491761</info><outline_data><hi              nt><![CDATA[IGNORE_OPTIM_EMBEDDED_HINTS]]></hint><hint><![CDATA[OPTIMIZER_FEATUR              ES_ENABLE('12.1.0.1')]]></hint><hint><![CDATA[DB_VERSION('12.1.0.1')]]></hint><h              int><![CDATA[ALL_ROWS]]></hint><hint><![CDATA[OUTLINE_LEAF(@"SEL$F5BB74E1")]]></              hint><hint><![CDATA[MERGE(@"SEL$2")]]></hint><hint><![CDATA[OUTLINE(@"SEL$1")]]>              </hint><hint><![CDATA[OUTLINE(@"SEL$2")]]></hint><hint><![CDATA[FULL(@"SEL$F5BB7              4E1" "P"@"SEL$2")]]></hint><hint><![CDATA[INDEX_FFS(@"SEL$F5BB74E1" "O"@"SEL$2"              ("ORDER_ITEMS"."ORDER_ID" "ORDER_ITEMS"."PRODUCT_ID"))]]></hint><hint><![CDATA[I              NDEX(@"SEL$F5BB74E1" "O"@"SEL$1" ("ORDERS"."ORDER_ID"))]]></hint><hint><![CDATA[              LEADING(@"SEL$F5BB74E1" "P"@"SEL$2" "O"@"SEL$2" "O"@"SEL$1")]]></hint><hint><![C              DATA[USE_HASH(@"SEL$F5BB74E1" "O"@"SEL$2")]]></hint><hint><![CDATA[USE_NL(@"SEL$              F5BB74E1" "O"@"SEL$1")]]></hint></outline_data></other_xml>            0 <other_xml><info type="db_version">12.1.0.1</info><info type="parse_schema"><![C              DATA["OE"]]></info><info type="plan_hash">1906736282</info><info type="plan_hash              _2">2579473118</info><outline_data><hint><![CDATA[IGNORE_OPTIM_EMBEDDED_HINTS]]>              </hint><hint><![CDATA[OPTIMIZER_FEATURES_ENABLE('12.1.0.1')]]></hint><hint><![CD              ATA[DB_VERSION('12.1.0.1')]]></hint><hint><![CDATA[ALL_ROWS]]></hint><hint><![CD              ATA[OUTLINE_LEAF(@"SEL$F5BB74E1")]]></hint><hint><![CDATA[MERGE(@"SEL$2")]]></hi              nt><hint><![CDATA[OUTLINE(@"SEL$1")]]></hint><hint><![CDATA[OUTLINE(@"SEL$2")]]>              </hint><hint><![CDATA[FULL(@"SEL$F5BB74E1" "P"@"SEL$2")]]></hint><hint><![CDATA[              INDEX(@"SEL$F5BB74E1" "O"@"SEL$1" ("ORDERS"."ORDER_ID"))]]></hint><hint><![CDATA              [INDEX(@"SEL$F5BB74E1" "O"@"SEL$2" ("ORDER_ITEMS"."ORDER_ID" "ORDER_ITEMS"."PROD              UCT_ID"))]]></hint><hint><![CDATA[LEADING(@"SEL$F5BB74E1" "P"@"SEL$2" "O"@"SEL$1              " "O"@"SEL$2")]]></hint><hint><![CDATA[USE_MERGE_CARTESIAN(@"SEL$F5BB74E1" "O"@"              SEL$1")]]></hint><hint><![CDATA[USE_NL(@"SEL$F5BB74E1" "O"@"SEL$2")]]></hint></o              utline_data></other_xml> ??2: SELECT /*+gather_plan_statistics*/ * FROM customers WHERE cust_state_province='CA' AND country_id='US'; SELECT * FROM TABLE(DBMS_XPLAN.DISPLAY_CURSOR(FORMAT=>'ALLSTATS LAST')); PLAN_TABLE_OUTPUT ------------------------------------- SQL_ID b74nw722wjvy3, child number 0 ------------------------------------- select /*+gather_plan_statistics*/ * from customers where CUST_STATE_PROVINCE='CA' and country_id='US' Plan hash value: 1683234692 -------------------------------------------------------------------------------------------------- | Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers | Reads | -------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 1 | | 29 |00:00:00.01 | 17 | 14 | |* 1 | TABLE ACCESS FULL| CUSTOMERS | 1 | 8 | 29 |00:00:00.01 | 17 | 14 | -------------------------------------------------------------------------------------------------- Predicate Information (identified by operation id): --------------------------------------------------- 1 - filter(("CUST_STATE_PROVINCE"='CA' AND "COUNTRY_ID"='US')) SELECT SQL_ID, CHILD_NUMBER, SQL_TEXT, IS_REOPTIMIZABLE FROM V$SQL WHERE SQL_TEXT LIKE 'SELECT /*+gather_plan_statistics*/%'; SQL_ID CHILD_NUMBER SQL_TEXT I ------------- ------------ ----------- - b74nw722wjvy3 0 select /*+g Y ather_plan_ statistics* / * from cu stomers whe re CUST_STA TE_PROVINCE ='CA' and c ountry_id=' US' EXEC DBMS_SPD.FLUSH_SQL_PLAN_DIRECTIVE; SELECT TO_CHAR(d.DIRECTIVE_ID) dir_id, o.OWNER, o.OBJECT_NAME, o.SUBOBJECT_NAME col_name, o.OBJECT_TYPE, d.TYPE, d.STATE, d.REASON FROM DBA_SQL_PLAN_DIRECTIVES d, DBA_SQL_PLAN_DIR_OBJECTS o WHERE d.DIRECTIVE_ID=o.DIRECTIVE_ID AND o.OWNER IN ('SH') ORDER BY 1,2,3,4,5; DIR_ID OWNER OBJECT_NAME COL_NAME OBJECT TYPE STATE REASON ----------------------- ----- ------------- ----------- ------ ---------------- ----- ------------------------ 1484026771529551585 SH CUSTOMERS COUNTRY_ID COLUMN DYNAMIC_SAMPLING NEW SINGLE TABLE CARDINALITY MISESTIMATE 1484026771529551585 SH CUSTOMERS CUST_STATE_ COLUMN DYNAMIC_SAMPLING NEW SINGLE TABLE CARDINALITY PROVINCE MISESTIMATE 1484026771529551585 SH CUSTOMERS TABLE DYNAMIC_SAMPLING NEW SINGLE TABLE CARDINALITY MISESTIMATE SELECT /*+gather_plan_statistics*/ * FROM customers WHERE cust_state_province='CA' AND country_id='US'; ELECT * FROM TABLE(DBMS_XPLAN.DISPLAY_CURSOR(FORMAT=>'ALLSTATS LAST')); PLAN_TABLE_OUTPUT ------------------------------------- SQL_ID b74nw722wjvy3, child number 1 ------------------------------------- select /*+gather_plan_statistics*/ * from customers where CUST_STATE_PROVINCE='CA' and country_id='US' Plan hash value: 1683234692 ----------------------------------------------------------------------------------------- | Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers | ----------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 1 | | 29 |00:00:00.01 | 17 | |* 1 | TABLE ACCESS FULL| CUSTOMERS | 1 | 29 | 29 |00:00:00.01 | 17 | ----------------------------------------------------------------------------------------- Predicate Information (identified by operation id): --------------------------------------------------- 1 - filter(("CUST_STATE_PROVINCE"='CA' AND "COUNTRY_ID"='US')) Note ----- - cardinality feedback used for this statement SELECT SQL_ID, CHILD_NUMBER, SQL_TEXT, IS_REOPTIMIZABLE FROM V$SQL WHERE SQL_TEXT LIKE 'SELECT /*+gather_plan_statistics*/%'; SQL_ID CHILD_NUMBER SQL_TEXT I ------------- ------------ ----------- - b74nw722wjvy3 0 select /*+g Y ather_plan_ statistics* / * from cu stomers whe re CUST_STA TE_PROVINCE ='CA' and c ountry_id=' US' b74nw722wjvy3 1 select /*+g N ather_plan_ statistics* / * from cu stomers whe re CUST_STA TE_PROVINCE ='CA' and c ountry_id=' US' SELECT /*+gather_plan_statistics*/ CUST_EMAIL FROM CUSTOMERS WHERE CUST_STATE_PROVINCE='MA' AND COUNTRY_ID='US'; SELECT * FROM TABLE(DBMS_XPLAN.DISPLAY_CURSOR(FORMAT=>'ALLSTATS LAST')); PLAN_TABLE_OUTPUT ------------------------------------- SQL_ID 3tk6hj3nkcs2u, child number 0 ------------------------------------- Select /*+gather_plan_statistics*/ cust_email From customers Where cust_state_province='MA' And country_id='US' Plan hash value: 1683234692 ------------------------------------------------------------------------------- |Id | Operation | Name | Starts|E-Rows|A-Rows| A-Time |Buffers| ------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 1 | | 2 |00:00:00.01| 16 | |*1 | TABLE ACCESS FULL| CUSTOMERS | 1 | 2| 2 |00:00:00.01| 16 | ----------------------------------------------------------------------------- Predicate Information (identified by operation id): --------------------------------------------------- 1 - filter(("CUST_STATE_PROVINCE"='MA' AND "COUNTRY_ID"='US')) Note ----- - dynamic sampling used for this statement (level=2) - 1 Sql Plan Directive used for this statement EXEC DBMS_SPD.FLUSH_SQL_PLAN_DIRECTIVE; SELECT TO_CHAR(d.DIRECTIVE_ID) dir_id, o.OWNER, o.OBJECT_NAME, o.SUBOBJECT_NAME col_name, o.OBJECT_TYPE, d.TYPE, d.STATE, d.REASON FROM DBA_SQL_PLAN_DIRECTIVES d, DBA_SQL_PLAN_DIR_OBJECTS o WHERE d.DIRECTIVE_ID=o.DIRECTIVE_ID AND o.OWNER IN ('SH') ORDER BY 1,2,3,4,5; DIR_ID OW OBJECT_NA COL_NAME OBJECT TYPE STATE REASON ------------------- -- --------- ---------- ------- --------------- ------------- ------------------------ 1484026771529551585 SH CUSTOMERS COUNTRY_ID COLUMN DYNAMIC_SAMPLING MISSING_STATS SINGLE TABLE CARDINALITY MISESTIMATE 1484026771529551585 SH CUSTOMERS CUST_STATE_ COLUMN DYNAMIC_SAMPLING MISSING_STATS SINGLE TABLE CARDINALITY PROVINCE MISESTIMATE 1484026771529551585 SH CUSTOMERS TABLE DYNAMIC_SAMPLING MISSING_STATS SINGLE TABLE CARDINALITY MISESTIMATE

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• Critique My Backup and Storage Plan

  - by MetaHyperBolic

  My current storage (RAID-1 off of a hardware RAID card) and backup (a spare drive) solutions for my home network are inadequate. I have too much data scattered on various one-off drives. It is time to evolve. Backups seem simple enough, at least: lots of big drives. However, I am bewildered by the number of choices for small home storage. The Drobo S looks appealing. So does the ReadyNAS. I am not looking for bunches of shiny features, I'm mostly interested in reliability. I am not interested in building Yet Another PC to create a file server or doing something in the cloud, or whatever. I'm stupid, so I am keeping it simple. Requirements for Main Volume: Starting working space roughly 2TB, with options for growth up to 5TB RAID or something RAID-like with at least one parity drive eSATA II for speed during backups Ability to shut down gracefully when alerted of low power by a UPS Optional but Desirable: Will take 2TB drives now with options for the larger 3TB drives coming in 2010-2011 Optional but Desirable: : RAID-6 or something similar, with two parity drives Optional but Desirable: : Hot spare Ethernet connection not required, as the volume will be shared via the same machines which runs my home print server Backups: Backup performed via ROBOCOPY in mirror mode to an external hard drive via a eSATA II connection. Start with rotating between two external 2TB hard drives, will go up to six external 2TB drives. Start with a weekly backup, move to a bi-weekly backup as more drives are added. Move to 3TB drives as the size of my main volume increases. Backup drives will be stored on an off-site location. Hard drives: I plan on buying all of the same model, but different batches from different vendors. I found a "burn-in" utility with which I can pound away on the drives for a couple of weeks before adding them to the backup pool or the main volume. I estimate that I am looking at roughly $1,500 to start, once I start throwing in two TB drives for backup and four for storage. So, are there any obvious flaws in my plan? What have I overlooked? Any suggestions for the storage device for my main volume that fits my requirements? Or do I just keep it simple, 2 drives in RAID-1, then perform due diligence with my backups, accepting that I will have to buy a whole new unit when my data grows past 2TB?

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• Building an SSL server farm

  - by dan

  I'm interested in building the the architecture in the article referenced below. I currently have a modestly-priced layer-4 load balancer and my application servers are the SSL endpoints. I want to put an SSL server farm in between my load balancer and my app servers. Then I will put another inexpensive load balancer between the SSL farm and my app servers, to do layer-7 routing. My web application has a fairly high amount of consumer traffic, that 6 servers can handle at about 50% capacity. Additionally, I have infrastructure traffic that is several orders of magnitude heavier than my consumer traffic. This is data coming in from all over the world that must integrate with my web application in real time. In total I have 18 app servers to handle all the traffic, plus 6 database servers. I will be adding 6 more app servers over the next 2 weeks and another 6 the 2 weeks after that. Conservatively, I estimate I will need to scale to 120 servers by the end of the year. My motivation right now is to separate the consumer traffic from the infrastructure traffic. The consumer traffic is higher priority than the infrastructure traffic and I cannot allow a stampede on the infrastructure side to take down my consumer-facing servers. Having a website that is always up is the top priority. However if there is a failure in one of the consumer app servers, I want to route that traffic to the servers designated for infrastructure traffic. The complication is that all the traffic is addressed using the same hostname and is nearly 100% https. The only way in my case to distinguish infrastructure from consumer traffic is by URL (poor architecture I inherited), so I need a layer 7 load balancer to be able to route. However for that to work I need either a fancy hardware-based SSL terminator or an SSL server farm as described above. Because my user base is rapidly scaling, I worry that if I go down the hardware path it will become very expensive very fast, especially since I will need 4 of everything for high availability (2 identical setups in 2 facilities). Meanwhile, the above diagram seems very flexible and more horizontally scalable. Has anyone built this before? Are there pre-built configurations? What considerations should I make and what software should I use (I've heard of people using apache with mod-ssl, nginx, and stunnel)? Also, when does it make sense to buy an expensive load balancer vs building an SSL server farm? http://1wt.eu/articles/2006_lb/index_05.html

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• My Interview with Microsoft

  - by Victor Hurdugaci

  This post is for those who want to apply or have already applied (but not finished the interview) for a Microsoft Job. The recruitment process is quite similar for everyone and consists of a few steps. Application E-Mail Interview Phone Interview On Site Interview I will tell you my story and how I went through the four phases. 1. Application My blog's title (Ex Nihilo Nihil Fit) means "Nothing Comes Out of Nothing". You can't get a job at Microsoft by not doing anything - this is true for anything else. The first step you need to complete is the application process. For this, many options are available. You can... ... apply online on Microsoft's Careers website as I did ... send your CV to different e-mail addresses (there are some dedicated e-mails for different positions) ... apply through some 3rd party organization (job shop, campus recruitment, job agency, etc) On MS Careers you just have to post your CV and choose the job you want. That's all! No recommendation letter, no cover letter, no nothing. Of course, not every CV passes the selection process. Here are some tips for improving your resume (worked for me): Don't write it just before applying! Write a draft version, wait a few days and then review it. This way you will find a lot of mistakes and stupid things you wrote initially. If you review it immediately after writing, your mind will not be criticism oriented and will just ignore mistakes. Repeat the write-wait-review process as many times as necessary, until you find that the review revealed no mistakes. After you did the final review and the CV is bullet-proof, ask others to review it. They will definitely find inconsistencies and mistakes and this will make you feel stupid. This is good because will open your eyes will make you go into an 'I want to improve' mode. You'll try to correct everything. After you come up with a modified version go again through steps 1 and 2. Repeat this as many times as necessary. [Special thanks to Lucian Sasu, Nadia Comanici, Andrei Ciobanu, Monica Balan and Lavinia Tanase for reviewing my CV!] Make it short and give only relevant facts. Initially, I come up with a 5 pages CV because I wrote every single technology with which I worked. There were a lot irrelevant things, I wrote Windows Workflow Foundation just because I played with it for a few days. I added extensive descriptions for every project, made a personal details section (name, birth date, address, etc) of 1/2 page. Others suggested to cut everything that was not necessary. You don't need to give extensive descriptions, just add a few words. For example, I wrote "VS Image Visualizer - Visual Studio 2008 debug visualizer for images" and added a link to the project's page - you submit formatted andcan embed links. Add something that makes it different. I don't know if this makes a difference, but I added some lines to separate items just like in the picture below. Definitely Microsoft gets thousands of CVs per day. You need something special. Don't lie! Tell exactly what you did and what is the proficiency level of your skills. For example, don't write "Advanced" for UML if you don't know the difference between composition and aggregation. Be realistic and don't under/over estimate yourself. Use the spell chick. Make sure everything is written in correct English and there are no grammar/spelling mistakes. Noddy likes a WC with grammar mi takes. You mght fail just because of that. Once you completed your CV, choose the job that suits best your needs, apply and wait... The waiting is a problem because all these big companies like Microsoft, Google, Mozilla, Apple, etc. will contact you only if they find something interesting in your application. If you're not suitable, then no rejection is sent. I applied for an Intern Software Development Engineer position at Microsoft Redmond. I cannot apply for a full time position because I want to finish the master program on time, in the next summer - an internship is just what I need. 2. E-Mail Interview January 20, 2010. Two months since I submitted the CV. I wasn't hoping anymore that MS will contact me, when I got an e-mail titled: "Victor Hurdugaci ES DK" from Holly Peterson saying: Read more >>

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• Performance considerations for common SQL queries

  - by Jim Giercyk

  Originally posted on: http://geekswithblogs.net/NibblesAndBits/archive/2013/10/16/performance-considerations-for-common-sql-queries.aspxSQL offers many different methods to produce the same results.  There is a never-ending debate between SQL developers as to the “best way” or the “most efficient way” to render a result set.  Sometimes these disputes even come to blows….well, I am a lover, not a fighter, so I decided to collect some data that will prove which way is the best and most efficient.  For the queries below, I downloaded the test database from SQLSkills:  http://www.sqlskills.com/sql-server-resources/sql-server-demos/.  There isn’t a lot of data, but enough to prove my point: dbo.member has 10,000 records, and dbo.payment has 15,554.  Our result set contains 6,706 records. The following queries produce an identical result set; the result set contains aggregate payment information for each member who has made more than 1 payment from the dbo.payment table and the first and last name of the member from the dbo.member table.   /*************/ /* Sub Query  */ /*************/ SELECT  a.[Member Number] ,         m.lastname ,         m.firstname ,         a.[Number Of Payments] ,         a.[Average Payment] ,         a.[Total Paid] FROM    ( SELECT    member_no 'Member Number' ,                     AVG(payment_amt) 'Average Payment' ,                     SUM(payment_amt) 'Total Paid' ,                     COUNT(Payment_No) 'Number Of Payments'           FROM      dbo.payment           GROUP BY  member_no           HAVING    COUNT(Payment_No) > 1         ) a         JOIN dbo.member m ON a.[Member Number] = m.member_no         /***************/ /* Cross Apply  */ /***************/ SELECT  ca.[Member Number] ,         m.lastname ,         m.firstname ,         ca.[Number Of Payments] ,         ca.[Average Payment] ,         ca.[Total Paid] FROM    dbo.member m         CROSS APPLY ( SELECT    member_no 'Member Number' ,                                 AVG(payment_amt) 'Average Payment' ,                                 SUM(payment_amt) 'Total Paid' ,                                 COUNT(Payment_No) 'Number Of Payments'                       FROM      dbo.payment                       WHERE     member_no = m.member_no                       GROUP BY  member_no                       HAVING    COUNT(Payment_No) > 1                     ) ca /********/                    /* CTEs  */ /********/ ; WITH    Payments           AS ( SELECT   member_no 'Member Number' ,                         AVG(payment_amt) 'Average Payment' ,                         SUM(payment_amt) 'Total Paid' ,                         COUNT(Payment_No) 'Number Of Payments'                FROM     dbo.payment                GROUP BY member_no                HAVING   COUNT(Payment_No) > 1              ),         MemberInfo           AS ( SELECT   p.[Member Number] ,                         m.lastname ,                         m.firstname ,                         p.[Number Of Payments] ,                         p.[Average Payment] ,                         p.[Total Paid]                FROM     dbo.member m                         JOIN Payments p ON m.member_no = p.[Member Number]              )     SELECT  *     FROM    MemberInfo /************************/ /* SELECT with Grouping   */ /************************/ SELECT  p.member_no 'Member Number' ,         m.lastname ,         m.firstname ,         COUNT(Payment_No) 'Number Of Payments' ,         AVG(payment_amt) 'Average Payment' ,         SUM(payment_amt) 'Total Paid' FROM    dbo.payment p         JOIN dbo.member m ON m.member_no = p.member_no GROUP BY p.member_no ,         m.lastname ,         m.firstname HAVING  COUNT(Payment_No) > 1   We can see what is going on in SQL’s brain by looking at the execution plan.  The Execution Plan will demonstrate which steps and in what order SQL executes those steps, and what percentage of batch time each query takes.  SO….if I execute all 4 of these queries in a single batch, I will get an idea of the relative time SQL takes to execute them, and how it renders the Execution Plan.  We can settle this once and for all.  Here is what SQL did with these queries:   Not only did the queries take the same amount of time to execute, SQL generated the same Execution Plan for each of them.  Everybody is right…..I guess we can all finally go to lunch together!  But wait a second, I may not be a fighter, but I AM an instigator.     Let’s see how a table variable stacks up.  Here is the code I executed: /********************/ /*  Table Variable  */ /********************/ DECLARE @AggregateTable TABLE     (       member_no INT ,       AveragePayment MONEY ,       TotalPaid MONEY ,       NumberOfPayments MONEY     ) INSERT  @AggregateTable         SELECT  member_no 'Member Number' ,                 AVG(payment_amt) 'Average Payment' ,                 SUM(payment_amt) 'Total Paid' ,                 COUNT(Payment_No) 'Number Of Payments'         FROM    dbo.payment         GROUP BY member_no         HAVING  COUNT(Payment_No) > 1   SELECT  at.member_no 'Member Number' ,         m.lastname ,         m.firstname ,         at.NumberOfPayments 'Number Of Payments' ,         at.AveragePayment 'Average Payment' ,         at.TotalPaid 'Total Paid' FROM    @AggregateTable at         JOIN dbo.member m ON m.member_no = at.member_no In the interest of keeping things in groupings of 4, I removed the last query from the previous batch and added the table variable query.  Here’s what I got:     Since we first insert into the table variable, then we read from it, the Execution Plan renders 2 steps.  BUT, the combination of the 2 steps is only 22% of the batch.  It is actually faster than the other methods even though it is treated as 2 separate queries in the Execution Plan.  The argument I often hear against Table Variables is that SQL only estimates 1 row for the table size in the Execution Plan.  While this is true, the estimate does not come in to play until you read from the table variable.  In this case, the table variable had 6,706 rows, but it still outperformed the other queries.  People argue that table variables should only be used for hash or lookup tables.  The fact is, you have control of what you put IN to the variable, so as long as you keep it within reason, these results suggest that a table variable is a viable alternative to sub-queries. If anyone does volume testing on this theory, I would be interested in the results.  My suspicion is that there is a breaking point where efficiency goes down the tubes immediately, and it would be interesting to see where the threshold is. Coding SQL is a matter of style.  If you’ve been around since they introduced DB2, you were probably taught a little differently than a recent computer science graduate.  If you have a company standard, I strongly recommend you follow it.    If you do not have a standard, generally speaking, there is no right or wrong answer when talking about the efficiency of these types of queries, and certainly no hard-and-fast rule.  Volume and infrastructure will dictate a lot when it comes to performance, so your results may vary in your environment.  Download the database and try it!

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• Integrating Windows Form Click Once Application into SharePoint 2007 &ndash; Part 2 of 4

  - by Kelly Jones

  In my last post, I explained why we decided to use a Click Once application to solve our business problem. To quickly review, we needed a way for our business users to upload documents to a SharePoint 2007 document library in mass, set the meta data, set the permissions per document, and to do so easily. Let’s look at the pieces that make up our solution.  First, we have the Windows Form application.  This app is deployed using Click Once and calls SharePoint web services in order to upload files and then calls web services to set the meta data (SharePoint columns and permissions).  Second, we have a custom action.  The custom action is responsible for providing our users a link that will launch the Windows app, as well as passing values to it via the query string.  And lastly, we have the web services that the Windows Form application calls.  For our solution, we used both out of the box web services and a custom web service in order to set the column values in the document library as well as the permissions on the documents. Now, let’s look at the technical details of each of these pieces.  (All of the code is downloadable from here: )   Windows Form application deployed via Click Once The Windows Form application, called “Custom Upload”, has just a few classes in it: Custom Upload -- the form FileList.xsd -- the dataset used to track the names of the files and their meta data values SharePointUpload -- this class handles uploading the file SharePointUpload uses an HttpWebRequest to transfer the file to the web server. We had to change this code from a WebClient object to the HttpWebRequest object, because we needed to be able to set the time out value.  public bool UploadDocument(string localFilename, string remoteFilename) { bool result = true; //Need to use an HttpWebRequest object instead of a WebClient object // so we can set the timeout (WebClient doesn't allow you to set the timeout!) HttpWebRequest req = (HttpWebRequest)WebRequest.Create(remoteFilename); try { req.Method = "PUT"; req.Timeout = 60 * 1000; //convert seconds to milliseconds req.AllowWriteStreamBuffering = true; req.Credentials = System.Net.CredentialCache.DefaultCredentials; req.SendChunked = false; req.KeepAlive = true; Stream reqStream = req.GetRequestStream(); FileStream rdr = new FileStream(localFilename, FileMode.Open, FileAccess.Read); byte[] inData = new byte[4096]; int bytesRead = rdr.Read(inData, 0, inData.Length); while (bytesRead > 0) { reqStream.Write(inData, 0, bytesRead); bytesRead = rdr.Read(inData, 0, inData.Length); } reqStream.Close(); rdr.Close(); System.Net.HttpWebResponse response = (HttpWebResponse)req.GetResponse(); if (response.StatusCode != HttpStatusCode.OK && response.StatusCode != HttpStatusCode.Created) { String msg = String.Format("An error occurred while uploading this file: {0}\n\nError response code: {1}", System.IO.Path.GetFileName(localFilename), response.StatusCode.ToString()); LogWarning(msg, "2ACFFCCA-59BA-40c8-A9AB-05FA3331D223"); result = false; } } catch (Exception ex) { LogException(ex, "{E9D62A93-D298-470d-A6BA-19AAB237978A}"); result = false; } return result; } The class also contains the LogException() and LogWarning() methods. When the application is launched, it parses the query string for some initial values.  The query string looks like this: string queryString = "Srv=clickonce&Sec=N&Doc=DMI&SiteName=&Speed=128000&Max=50"; This Srv is the path to the server (my Virtual Machine is name “clickonce”), the Sec is short for security – meaning HTTPS or HTTP, the Doc is the shortcut for which document library to use, and SiteName is the name of the SharePoint site.  Speed is used to calculate an estimate for download speed for each file.  We added this so our users uploading documents would realize how long it might take for clients in remote locations (using slow WAN connections) to download the documents. The last value, Max, is the maximum size that the SharePoint site will allow documents to be.  This allowed us to give users a warning that a file is too large before we even attempt to upload it. Another critical piece is the meta data collection.  We organized our site using SharePoint content types, so when the app loads, it gets a list of the document library’s content types.  The user then select one of the content types from the drop down list, and then we query SharePoint to get a list of the fields that make up that content type.  We used both an out of the box web service, and one that we custom built, in order to get these values. Once we have the content type fields, we then add controls to the form.  Which type of control we add depends on the data type of the field.  (DateTime pickers for date/time fields, etc)  We didn’t write code to cover every data type, since we were working with a limited set of content types and field data types. Here’s a screen shot of the Form, before and after someone has selected the content types and our code has added the custom controls:     The other piece of meta data we collect is the in the upper right corner of the app, “Users with access”.  This box lists the different SharePoint Groups that we have set up and by checking the boxes, the user can set the permissions on the uploaded documents. All of this meta data is collected and submitted to our custom web service, which then sets the values on the documents on the list.  We’ll look at these web services in a future post. In the next post, we’ll walk through the Custom Action we built.

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• Oracle RightNow CX for Good Customer Experiences

  - by Andreea Vaduva

  Oracle RightNow CX is all about the customer experience, it’s about understanding what drives a good interaction and it’s about delivering a solution which works for our customers and by extension, their customers. One of the early guiding principles of Oracle RightNow was an 8-point strategy to providing good customer experiences. Establish a knowledge foundation Empowering the customer Empower employees Offer multi-channel choice Listen to the customer Design seamless experiences Engage proactively Measure and improve continuously The application suite provides all of the tools necessary to deliver a rewarding, repeatable and measurable relationship between business and customer. The Knowledge Authoring tool provides gap analysis, WYSIWIG editing (and includes HTML rich content for non-developers), multi-level categorisation, permission based publishing and Web self-service publishing. Oracle RightNow Customer Portal, is a complete web application framework that enables businesses to control their own end-user page branding experience, which in turn will allow customers to self-serve. The Contact Centre Experience Designer builds a combination of workspaces, agent scripting and guided assistances into a Desktop Workflow. These present an agent with the tools they need, at the time they need them, providing even the newest and least experienced advisors with consistently accurate and efficient information, whilst guiding them through the complexities of internal business processes. Oracle RightNow provides access points for customers to feedback about specific knowledge articles or about the support site in general. The system will generate ‘incidents’ based on the scoring of the comments submitted. This makes it easy to view and respond to customer feedback. It is vital, more now than ever, not to under-estimate the power of the social web – Facebook, Twitter, YouTube – they have the ability to cause untold amounts of damage to businesses with a single post – witness musician Dave Carroll and his protest song on YouTube, posted in response to poor customer services from an American airline. The first day saw 150,000 views and is currently at 12,011,375. The Times reported that within 4 days of the post, the airline’s stock price fell by 10 percent, which represented a cost to shareholders of $180 million dollars. It is a universally acknowledged fact, that when customers are unhappy, they will not come back, and, generally speaking, it only takes one bad experience to lose a customer. The idea that customer loyalty can be regained by using social media channels was the subject of a 2011 Survey commissioned by RightNow and conducted by Harris Interactive. The survey discovered that 68% of customers who posted a negative review about a holiday on a social networking site received a response from the business. It further found that 33% subsequently posted a positive review and 34% removed the original negative review. Cloud Monitor provides the perfect mechanism for seeing what is being said about a business on public Facebook pages, Twitter or YouTube posts; it allows agents to respond proactively – either by creating an Oracle RightNow incident or by using the same channel as the original post. This leaves step 8 – Measuring and Improving: How does a business know whether it’s doing the right thing? How does it know if its customers are happy? How does it know if its staff are being productive? How does it know if its staff are being effective? Cue Oracle RightNow Analytics – fully integrated across the entire platform – Service, Marketing and Sales – there are in excess of 800 standard reports. If this were not enough, a large proportion of the database has been made available via the administration console, allowing users without any prior database experience to write their own reports, format them and schedule them for e-mail delivery to a distribution list. It handles the complexities of table joins, and allows for the manipulation of data with ease. Oracle RightNow believes strongly in the customer owning their solution, and to provide the best foundation for success, Oracle University can give you the RightNow knowledge and skills you need. This is a selection of the courses offered: RightNow Customer Service Administration Rel 12.02 (3 days) Available as In Class and Live Virtual Class (Release 11.11 is available as In Class, Live Virtual Class and Training On Demand) This course familiarises users with the tasks and concepts needed to configure and maintain their system. RightNow Customer Portal Designer and Contact Center Experience Designer Administration Rel 12.02 (2 days) Available as In Class and Live Virtual Class (Release 11.11 is available as In Class, Live Virtual Class and Training On Demand) This course introduces basic CP structure and how to make changes to the look, feel and behaviour of their self-service pages RightNow Analytics Rel 12.02 (2 days) Available as In Class, Live Virtual Class and Training On Demand (Release 11.11 is available as In Class and Live Virtual Class) This course equips users with the skills necessary to understand data supplied by standard reports and to create custom reports RightNow Integration and Customization For Developers Rel 12.02 (5-days) Available as In Class and Live Virtual Class (Release 11.11 is available as In Class, Live Virtual Class and Training On Demand) This course is for experienced web developers and offers an introduction to Add-In development using the Desktop Add-In Framework and introduces the core knowledge that developers need to begin integrating Oracle RightNow CX with other systems A full list of courses offered can be found on the Oracle University website. For more information and course dates please get in contact with your local Oracle University team. On top of the Service components, the suite also provides marketing tools, complex survey creation and tracking and sales functionality. I’m a fan of the application, and I think I’ve made that clear: It’s completely geared up to providing customers with support at point of need. It can be configured to meet even the most stringent of business requirements. Oracle RightNow is passionate about, and committed to, providing the best customer experience possible. Oracle RightNow CX is the application that makes it possible. About the Author: Sarah Anderson worked for RightNow for 4 years in both in both a consulting and training delivery capacity. She is now a Senior Instructor with Oracle University, delivering the following Oracle RightNow courses: RightNow Customer Service Administration RightNow Analytics RightNow Customer Portal Designer and Contact Center Experience Designer Administration RightNow Marketing and Feedback

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• CPU Usage in Very Large Coherence Clusters

  - by jpurdy

  When sizing Coherence installations, one of the complicating factors is that these installations (by their very nature) tend to be application-specific, with some being large, memory-intensive caches, with others acting as I/O-intensive transaction-processing platforms, and still others performing CPU-intensive calculations across the data grid. Regardless of the primary resource requirements, Coherence sizing calculations are inherently empirical, in that there are so many permutations that a simple spreadsheet approach to sizing is rarely optimal (though it can provide a good starting estimate). So we typically recommend measuring actual resource usage (primarily CPU cycles, network bandwidth and memory) at a given load, and then extrapolating from those measurements. Of course there may be multiple types of load, and these may have varying degrees of correlation -- for example, an increased request rate may drive up the number of objects "pinned" in memory at any point, but the increase may be less than linear if those objects are naturally shared by concurrent requests. But for most reasonably-designed applications, a linear resource model will be reasonably accurate for most levels of scale. However, at extreme scale, sizing becomes a bit more complicated as certain cluster management operations -- while very infrequent -- become increasingly critical. This is because certain operations do not naturally tend to scale out. In a small cluster, sizing is primarily driven by the request rate, required cache size, or other application-driven metrics. In larger clusters (e.g. those with hundreds of cluster members), certain infrastructure tasks become intensive, in particular those related to members joining and leaving the cluster, such as introducing new cluster members to the rest of the cluster, or publishing the location of partitions during rebalancing. These tasks have a strong tendency to require all updates to be routed via a single member for the sake of cluster stability and data integrity. Fortunately that member is dynamically assigned in Coherence, so it is not a single point of failure, but it may still become a single point of bottleneck (until the cluster finishes its reconfiguration, at which point this member will have a similar load to the rest of the members). The most common cause of scaling issues in large clusters is disabling multicast (by configuring well-known addresses, aka WKA). This obviously impacts network usage, but it also has a large impact on CPU usage, primarily since the senior member must directly communicate certain messages with every other cluster member, and this communication requires significant CPU time. In particular, the need to notify the rest of the cluster about membership changes and corresponding partition reassignments adds stress to the senior member. Given that portions of the network stack may tend to be single-threaded (both in Coherence and the underlying OS), this may be even more problematic on servers with poor single-threaded performance. As a result of this, some extremely large clusters may be configured with a smaller number of partitions than ideal. This results in the size of each partition being increased. When a cache server fails, the other servers will use their fractional backups to recover the state of that server (and take over responsibility for their backed-up portion of that state). The finest granularity of this recovery is a single partition, and the single service thread can not accept new requests during this recovery. Ordinarily, recovery is practically instantaneous (it is roughly equivalent to the time required to iterate over a set of backup backing map entries and move them to the primary backing map in the same JVM). But certain factors can increase this duration drastically (to several seconds): large partitions, sufficiently slow single-threaded CPU performance, many or expensive indexes to rebuild, etc. The solution of course is to mitigate each of those factors but in many cases this may be challenging. Larger clusters also lead to the temptation to place more load on the available hardware resources, spreading CPU resources thin. As an example, while we've long been aware of how garbage collection can cause significant pauses, it usually isn't viewed as a major consumer of CPU (in terms of overall system throughput). Typically, the use of a concurrent collector allows greater responsiveness by minimizing pause times, at the cost of reducing system throughput. However, at a recent engagement, we were forced to turn off the concurrent collector and use a traditional parallel "stop the world" collector to reduce CPU usage to an acceptable level. In summary, there are some less obvious factors that may result in excessive CPU consumption in a larger cluster, so it is even more critical to test at full scale, even though allocating sufficient hardware may often be much more difficult for these large clusters.

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• Database Partitioning and Multiple Data Source Considerations

  - by Jeffrey McDaniel

  With the release of P6 Reporting Database 3.0 partitioning was added as a feature to help with performance and data management.  Careful investigation of requirements should be conducting prior to installation to help improve overall performance throughout the lifecycle of the data warehouse, preventing future maintenance that would result in data loss. Before installation try to determine how many data sources and partitions will be required along with the ranges.  In P6 Reporting Database 3.0 any adjustments outside of defaults must be made in the scripts and changes will require new ETL runs for each data source.  Considerations: 1. Standard Edition or Enterprise Edition of Oracle Database.   If you aren't using Oracle Enterprise Edition Database; the partitioning feature is not available. Multiple Data sources are only supported on Enterprise Edition of Oracle   Database. 2. Number of Data source Ids for partitioning during configuration.   This setting will specify how many partitions will be allocated for tables containing data source information.  This setting requires some evaluation prior to installation as       there are repercussions if you don't estimate correctly.   For example, if you configured the software for only 2 data sources and the partition setting was set to 2, however along came a 3rd data source.  The necessary steps to  accommodate this change are as follows: a) By default, 3 partitions are configured in the Reporting Database scripts. Edit the create_star_tables_part.sql script located in <installation directory>\star\scripts   and search for partition.  You’ll see P1, P2, P3.  Add additional partitions and sub-partitions for P4 and so on. These will appear in several areas.  (See P6 Reporting Database 3.0 Installation and Configuration guide for more information on this and how to adjust partition ranges). b) Run starETL -r.  This will recreate each table with the new partition key.  The effect of this step is that all tables data will be lost except for history related tables.   c) Run starETL for each of the 3 data sources (with the data source # (starETL.bat "-s2" -as defined in P6 Reporting Database 3.0 Installation and Configuration guide) The best strategy for this setting is to overestimate based on possible growth.  If during implementation it is deemed that there are atleast 2 data sources with possibility for growth, it is a better idea to set this setting to 4 or 5, allowing room for the future and preventing a ‘start over’ scenario. 3. The Number of Partitions and the Number of Months per Partitions are not specific to multi-data source.  These settings work in accordance to a sub partition of larger tables with regard to time related data.  These settings are dataset specific for optimization.  The number of months per partition is self explanatory, optimally the smaller the partition, the better query performance so if the dataset has an extremely large number of spread/history records, a lower number of months is optimal.  Working in accordance with this setting is the number of partitions, this will determine how many "buckets" will be created per the number of months setting.  For example, if you kept the default for # of partitions of 3, and select 2 months for each partitions you would end up with: -1st partition, 2 months -2nd partition, 2 months -3rd partition, all the remaining records Therefore with records to this setting, it is important to analyze your source db spread ranges and history settings when determining the proper number of months per partition and number of partitions to optimize performance.  Also be aware the DBA will need to monitor when these partition ranges will fill up and when additional partitions will need to be added.  If you get to the final range partition and there are no additional range partitions all data will be included into the last partition. 

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• Python: nonblocking read from stdout of threaded subprocess

  - by sberry2A

  I have a script (worker.py) that prints unbuffered output in the form... 1 2 3 . . . n where n is some constant number of iterations a loop in this script will make. In another script (service_controller.py) I start a number of threads, each of which starts a subprocess using subprocess.Popen(stdout=subprocess.PIPE, ...); Now, in my main thread (service_controller.py) I want to read the output of each thread's worker.py subprocess and use it to calculate an estimate for the time remaining till completion. I have all of the logic working that reads the stdout from worker.py and determines the last printed number. The problem is that I can not figure out how to do this in a non-blocking way. If I read a constant bufsize then each read will end up waiting for the same data from each of the workers. I have tried numerous ways including using fcntl, select + os.read, etc. What is my best option here? I can post my source if needed, but I figured the explanation describes the problem well enough. Thanks for any help here. EDIT Adding sample code I have a worker that starts a subprocess. class WorkerThread(threading.Thread): def __init__(self): self.completed = 0 self.process = None self.lock = threading.RLock() threading.Thread.__init__(self) def run(self): cmd = ["/path/to/script", "arg1", "arg2"] self.process = subprocess.Popen(cmd, stdout=subprocess.PIPE, bufsize=1, shell=False) #flags = fcntl.fcntl(self.process.stdout, fcntl.F_GETFL) #fcntl.fcntl(self.process.stdout.fileno(), fcntl.F_SETFL, flags | os.O_NONBLOCK) def get_completed(self): self.lock.acquire(); fd = select.select([self.process.stdout.fileno()], [], [], 5)[0] if fd: self.data += os.read(fd, 1) try: self.completed = int(self.data.split("\n")[-2]) except IndexError: pass self.lock.release() return self.completed I then have a ThreadManager. class ThreadManager(): def __init__(self): self.pool = [] self.running = [] self.lock = threading.Lock() def clean_pool(self, pool): for worker in [x for x in pool is not x.isAlive()]: worker.join() pool.remove(worker) del worker return pool def run(self, concurrent=5): while len(self.running) + len(self.pool) > 0: self.clean_pool(self.running) n = min(max(concurrent - len(self.running), 0), len(self.pool)) if n > 0: for worker in self.pool[0:n]: worker.start() self.running.extend(self.pool[0:n]) del self.pool[0:n] time.sleep(.01) for worker in self.running + self.pool: worker.join() and some code to run it. threadManager = ThreadManager() for i in xrange(0, 5): threadManager.pool.append(WorkerThread()) threadManager.run() I have stripped out a log of the other code in hopes to try to pinpoint the issue.

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• Removing expired certificates from LDS (new ver of ADAM)

  - by jonthebrewer

  Hi all. This is my situation: We are in the process of replacing a certificate store currently hosted on Sun's iPlanet with Microsoft's Lightweight Directory Services (new version of ADAM with Server 2008). These certificates have been imported into LDS into an application partition (say o=myorg, C=AU). Under this structure I have around 40,000 OU's each one representing a customer under each customers OU are one or more user (iNetOrg) objects (around 60,000 in all). In each user are one or more certificates in the UserCertificate attribute. A combination of in-house written application code and proprietory PKI code reads and publishes these certficates to validate financial transactions. As the LDAP path of the certificates is stored within the customer certificates (and within the application code) and there is zero appetite for changing any of the code, I have had to pick up the iPlanet directory as a whole and dump it in LDS in the same structure. (I will not be using or hosting a Microsoft CA, just implementing an LDAP compliant directory to host these certificates) We have fully tested the application using the data in LDS and everything works fine - here is my dilema and question (finally, phew!) There was no process put in place for removing revoked or expired certificates, consequently the vast majority of the data is completely useless, the system has been running for about 8 years! I have done a quick analysis and I estimate that at least 80% of the data is no longer valid. As I am taking on responsibility for managing the directory I would like to start with a clean directory. Does anyone have any idea how I can cleanup these expired certificates. I am not a highly experienced scripter but have some background in VB. I have been researching the use of CAPICOM and have a feeling this may be able to be used but in exactly what way I am not sure?? I would prefer to write a script that I could specify an expiration date (say any certs that expired prior to 2010) then run against the LDS paritition. This way I can reuse the script periodically to cleanup the directory (as mentioned above - I have no way to adjust the applications that are writing the certs, this is with a third party). Another, less attractive, alternative is to massage the LDIF file (2.7 million lines!) to rip the certs out prior to the import Any help and advice MUCH appreciated. Cheers Jon

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